Difference between protagonist and antagonist?

A protagonist is the "hero" or main character.

An antagonist is the 'villian" or opposition to the main character.

A protagonist is a character that drives the plot, moves the story forward. They are typically the main character, and they can be the "hero" of the story, but not necessarily. Antagonists aren't necessarily the "villains" either ... That doesn't have to mean conflict between the protagonist and the antagonist.