system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between a progressive and a liberal?
gpt
Progressive is the more appropriate opposite to conservative.  A conservative looks at the world moving forward and yells, "Stop!  You're going too fast!  You'll disrupt our tradition of being who we are and what makes us great."  A progressive, as simply indicated by its name, says, "Full steam ahead!  Move forward because we'll get left behind if we tarry and then we'll no longer be as great."

The question becomes *how* you want to stay put or move forward.  The "Progressive Era," the presidencies of Teddy Roosevelt, Taft, and Wilson, actually saw different parties taking up the progressive label (Roosevelt and Taft were Republicans [what we'd call left wing today] and Wilson was a Democrat [what we'd call right wing today]).  Left wing denotes a more liberal use of the government, whereas right wing denotes a more conservative use of the government.

And this is why it gets a little confusing.  We use "conservative" to mean two different, albeit related, things.  We use it in one sense as "to conserve the status quo" - this is the foil to progressive; but we also use it in the sense of "restrained, careful not to overstep" - this is the foil to liberal.  To see why these aren't necessarily equivalent definitions, you could think of a situation where the government, through tremendous oversight, can make us maintain the status quo - halting any innovation, stifling social progress, mandating today's traditions be followed, etc.  In American politics though, due to the inherently dichotomous party system, this (ostensibly allegedly) isn't an important distinction and conservative can simultaneously have both definitions and progressive/liberal be flipsides of the same coin.