I tend to see Progressive mainly as being “in favor of progress”. Believing that we can and should make positive changes moving forward, and that we shouldn’t cling too hard to the past.
IME there’s certainly overlap with Liberalism, but with more willingness to compromise on big-government entitlement programs, and with more specific skepticism of corporate power and moneyed interests. The latter element,
BTW, being very much in keeping with Roosevelt’s Progressive Party Platform, from 1912.
"To destroy this invisible Government, to dissolve the unholy alliance between corrupt business and corrupt politics is the first task of the statesmanship of the day." - 1912 Progressive Party Platform, attributed to Theodore Roosevelt[1] and quoted again in his autobiography[2] where he connects Trusts and monopolies (sugar interests, Standard Oil, etc.) to Woodrow Wilson and William Howard Taft, and consequently both major political parties.