What is the difference between the terms "liberal" and "progressive" in American politics?

[Bluenorthwest]

37. I actually was not referring to you, so I guess your leap is also amazing.

I support what H2OMan is saying here. Words mean things, and those meanings are important. On DU, there are some who want to make one or the other of those words into a slur, they use the words in air quotes thusly "Progressives" or "Liberals" but usually it is progressive that is the word placed in quotes, the writers snarling their contempt for that which in fact is really themselves. When attempts to educate about actual language and definitions are made, this is a challenge for those who want to divide and disparage to use one or the other of two perfectly fine words as an insult. I have read, on DU, and I kid you not, posters snarling that they are liberals and they 'thank God I'm not a 'progressive'" which to me is a pile of nonsense unless one is seeking to use the term 'progressive' to mean something other than what it actually means.
I totally like that you posted this, it is an important conversation because many seem to think liberals and progressives are something other than nuanced terms that could, should and actually do apply to most DUers at various times around various issues. Anyone who can look at the Republican Party and feels the need to quarrel with other Democrats because 'I'm a progressive and they are a liberal' is not being helpful to our mutual goals and objectives.
Hope that clears it up. I just don't care for seeing Democrats attack Democrats over words that are not well understood, which is why I like this thread and your question very much.