What is the difference between antagonist and foil?

An antagonist is a character or force that opposes the main character, or protagonist, creating conflict within the story. A foil, on the other hand, is a character who contrasts with the protagonist, highlighting particular qualities or traits of that character. While the antagonist actively works against the protagonist's goals, a foil serves to enhance understanding of the protagonist by providing a comparison. Both serve distinct roles in character development and plot progression.