The difference between liberalism and progressivism is ideological.
Historically, liberalism started with John Locke, whose philosophy was superbly summarized, explained, and referenced to its sources, here; but the following will instead quote directly from those sources:
Locke (as the commentator said) “praises money as probably no one prior and after him,” because Locke’s 1689 Second Treatise on Government, Sections 49 & 50, asserted that only by means of money, “Man will begin presently to enlarge his Possessions” and thereby start to get beyond the crudest agriculturally based economy. Locke then said in Sec. 124 that “The great and chief end, therefore, of men’s uniting into commonwealths, and putting themselves under government, is the preservation of their property.” In other words: money enables wealth to grow, and government exists in order to protect wealth, not to serve nor protect people. Lord Acton, writing in 1877, criticized Locke’s philosophy because Locke’s “notion of liberty involves nothing more spiritual than the security of property, and is consistent with slavery and persecution.” That was the case about Locke because Locke’s philosophy wouldn’t have won any aristocratic sponsors at all, and would therefore simply have failed utterly and become lost to history, if it didn’t allow slavery, and — even more basically — allow unequal rights that depend upon the possession (and especially upon the inheritance) of wealth, and that generates respecting the wealthy (especially the hereditary wealthy) more than the poor (and with slaves being at the absolute bottom). Locke’s philosophy was affirmative toward the existing class-hierarchy, a property-based hierarchy. However, Lord Acton had, himself, been passionately committed to America’s slaveholding southern states’ Confederacy during the U.S. Civil War, because he believed more in the principle of local or home rule (as opposed to federal rule) than he opposed “slavery and persecution” (such as against slaves).
So: the entire aristocracy, except for the outright conservatives (which were the vast majority) amongst them, were hypocrites, and liberalism is based upon that hypocrisy, nothing which is internally consistent. Since it’s unadulterated hypocrisy, it is sloppy thinking, and it is this because otherwise it would be simply “Might makes right” — pure conservatism — unadorned with any pretenses to decency, and to equality of rights irrespective of wealth. In other words: Locke offered the aristocracy a way to consider themselves to be decent people no matter how bad they might actually be, and his intellectual offering to them required a lot of intellectual sloppiness. This is liberalism, at its very outset, and right up till today. It is stupid, but the super-rich consider it to be acceptable, and so some of them sponsor it, which enabled it to become a “classic.”
By contrast, progressivism is a total and unequivocal rejection of conservatism. It doesn’t respect wealth and the wealthy, nor does it despise the poor. It instead admires goodness which seeks no recompense or public honor therefore, but instead springs from as wide a compassion as possible (without regard to an individual’s race, creed, or ethnicity). And it despises greed, and rejects outright the “Greed is good” philosophy (a philosophy that’s consistent with both liberalism and conservatism; so, progressivism repudiates both). And it accords no honor to winning, and no shame to losing. The progressive (like anyone) wants to win, but only for a good cause, as “good” is accorded without any favoritism toward any individual or group or individuals, nor disfavoring of others, but purely with equal rights for all, to freedom and happiness and fulfillment.
Because progressives are committed to the good, they do passionately support the good against the evil; and, to them, the “good” are progressives, and the “evil” are proponents of might-makes-right. This is what progressivism is all about — the difference between progressivism and conservatism. By contrast with those polar-opposite ideologies, liberalism is merely in-between. It is every shade of gray, because it compromises between good and evil. As some liberals like to say, it is “nuanced.”
Might-makes-right — the very core of conservatism — is automatically favoring the rich against the poor, because, in the real world, money is power and the poor are therefore the weakest class of all. Locke’s First Treatise on Government, “Book I. Ch. XI. Who Heir?” (Sec. 107) goes even further into its conservative tradition of might-makes-right. It asserts that “the author” of the Bible (his God) is “affirming that the assignment of civil power is by divine institution, … so that no consideration, no act or art of man, can divert it from that person, to whom, by this divine right, it is assigned.” Liberalism not only accepts hereditary rule, but it rejects any sort of democracy, because, for a liberal, accountability is only to The Almighty, not to any mortal nor public of mortals. Thus, the founder of liberalism, Locke, said there that “it would be as much sacrilege for any one to be king, who was not Adam’s heir, as it would have been amongst the Jews,” because the will of The Almighty is eternal, and applies not merely in the past.
When America’s Founders refused even so much as to mention any god, and opened the U.S. Constitution with “We, the people of the United States, … do ordain and establish this Constitution,” it was an authentic break away from the past, because they were repudiating not only conservatism but liberalism, and were actually starting progressivism. They were doing this because accountability here was being ordained, in this new country — via its Constitution — to be accountability to the mortals, the public; and not to any The Almighty, at all. They chose to do this — break radically from the past. That act, from them, the U.S. Constitution, gave birth to progressivism — not merey to a new country. This Constitution served as the American Scripture, except that unlike any religious one, it included provisions for its own subsequent amendment, via the public’s representatives. Unlike any religious Scripture, it allowed itself to become improved. That, too (allowance for improvement), is a basic feature of progressivism, which contrasts starkly against conservatism (which relies instead upon some immutable Scripture).
Because a progressive favors equally the rights of all, and rejects unconditionally the supremacy of any nation above any other, a fundamental principle of progressivism is an utter rejection of imperialism (against which America’s Founders had waged their own Revolutionary War), and of any invasion of one country by another which has not become, nor been reasonably considered to pose a danger to become, invaded by that other, which it has invaded. During the War of 1812, Americans waged war to defend their largely democratic republic against imperial Britain’s invasion to re-seize this land. The imperialists committed aggression against Americans, after having lost the Revolutionary War to them. Consequently, for example: America, which since 1898 has itself unprovokedly invaded and sought to vassalize and exploit, more countries than any other nation, is perhaps the most conservative country, at least since around 1900. Today’s U.S. is, in this sense, profoundly anti-progressive and anti-American, because it has become the most imperialistic nation in the world, having taken the place of England, and of France, and of Spain, and of Germany, and of Portugal, and of Japan, and of Italy. America’s Constitution has now become overthrown. America today is ruled by ideological enemies of America’s Founders. Today’s America is unAmerican, in that deepest of all senses.
Consequently, to be a progressive in today’s America is to be ideologically rather isolated, alone with the Founders, in this now extremist conservative society, so alien to its own Constitution. It’s to be at a severe disadvantage, in this society. But, to a progressive, there is no assumption that the good shall be rewarded and that the evil shall be punished. There is a hope for that, but no expectation of it. Consequently, the progressive is a progressive not for personal gain but purely to do justice in the world. Recognizing that the world’s norm is profoundly unjust, a progressive seeks especially to aid the good against the evil, irrespective of the consequences to oneself.
Obviously, therefore, far more liberals than progressives exist. It’s not profitable to be progressive, but it is good to be progressive — and that’s a progressive’s main concern.
It’s important to be able to tell the difference between a liberal and a progressive. One reason that’s so difficult for so many people to do is that many liberals are ‘progressives’ in sheeps’ clothing — fakes — and the biggest policy-area where this is the case is in foreign policies, because whereas average voters know that politicians who fight against lowering their medical costs are bad, they don’t know (nor even care) nearly so much about international affairs. Here is a typical example of a ‘progressive‘ who is also a neoconservative (though garbing it in ‘progressive’ arguments). He favors “a democracy promotion agenda” like other liberals did in Iraq, Syria, Ukraine, etc. He doesn’t even so much as question that the Cold War was about ideology instead of about expanding the American empire. (How can anybody question that it wasn’t, after this? Is he really so ignorant? Or is the explanation something worse? He’s sufficiently ‘well-educated‘ so that it’s something worse. To put it as kindly as possible: he knows on which side his bread is buttered, and he cares more about that than he cares about truth and honesty.)
Locke, having been a liberal instead of a pure conservative, would not approve of today’s America, because by his basing his ethic upon property (wealth), he acknowledged the extreme evilness of conquest. Thus, “Book II. Ch. XVI. Of Conquest” in his Second Treatise on Government, states (Sec. 176):
That the aggressor, who puts himself into the state of war with another, and unjustly invades another man’s right, can, by such an unjust war, never come to have a right over the conquered, will be easily agreed by all men, who will not think, that robbers and pirates have a right of empire over whomsoever they have force enough to master; or that men are bound by promises, which unlawful force extorts from them. Should a robber break into my house, and with a dagger at my throat make me seal deeds to convey my estate to him, would this give him any title? Just such a title, by his sword, has an unjust conqueror, who forces me into submission. The injury and the crime is equal, whether committed by the wearer of a crown, or some petty villain. The title of the offender, and the number of his followers, make no difference in the offence, unless it be to aggravate it. The only difference is, great robbers punish little ones, to keep them in their obedience; but the great ones are rewarded with laurels and triumphs, because they are too big for the weak hands of justice in this world, and have the power in their own possession, which should punish offenders.
So: today’s U.S.A. stands condemned even in that compromised work, the foundation of liberalism. It stands condemned because John Locke wasn’t a pure conservative — in that passage, he clearly condemned might-makes-right, which he said pertained “in this world,” meaning not in the world of The Almighty, in a supposed afterlife, where power, supposedly, does reflect virtue.
By contrast, a progressive makes no assumption that power reflects virtue anywhere. The only reason for a progressive to be virtuous is to be virtuous — and not according to any ‘The Almighty’, but instead recognizing, from the progressive’s experience of this world, that if this world does reflect, in any sense, the will of ‘The Almighty’, then that Almighty is anything but virtuous — certainly not virtuous, at all. It’s not a progressive world — not at all. To be a progressive is to accept this fact, instead of to be deluded that there is some reward in ‘an afterlife’, because a progressive doesn’t expect to be rewarded for virtue, but, more likely, to be punished for it. (Consider whistleblowers as progressives, and almost all of them are punished for it.) To do something for a reward is commerce; it’s no political ideology, at all. So, again: there are very few progressives. Progressivism is no church which aims to increase the size of its flock (thereby compromising so much as to become worthless, even if it was not so before). Success is not its guidestar. Truth is. That’s what guides a progressive’s conscience. Thus, too, there is no progressive myth. None. A progressive accepts and recognizes history, but no myth. By contrast, a liberal, such as Locke, bases his ‘case’ upon whatever myth he chooses.
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PS, responding to a critic: A reader of this has objected: “Progressives are flawed human beings like everybody else. Yet Zuesse converts them into morally pristine übermenchen with all other human motivations outside of his progressive ideals being invalid. BTW, so Progressives never seek to maximize their economic well-being? They never game the system? They are never arrogant and self-serving? They never ignore the laws of unintended consequences? The laws of conflicting objectives don’t apply to them? I’d like to see a follow-on SCF article that critiques Zuesse’s claim to Progressism’s claim to outright and absolute moral supremacy. And then let the readers compare and contrast.” What he described there are liberals, not progressives. The title of this article is “The Difference Between Being a Liberal and Being a Progressive.” He missed its point. However, of course all people “are flawed human beings.” That’s just a cliché. And, of course, within the bounds of decency, progressives do “seek to maximize their economic well-being.” But all of his objection ignores the article’s argument and evidence. As regards evidence, here is more.