What's the difference between an antithesis and a foil

A foil is a character that is the opposite of the protagonist, but not necessarily in a bad way. It only means they have opposite qualities--it does not mean that they are the antagonist of the main character. Antithetical character are normally their "enemies"--they are the antithesis. Think antithesis of the main character.

Ihaven't read it but i hope u find ya answer