Foils

A foil is a character who serves as a contrast to another character, usually the protagonist, in order to highlight the differences between them.

Examples

 * 1) Toy Story 3: Woody and Lotso
 * 2) *Similarities:
 * 3) **Both serve as leaders of their toy families.
 * 4) *Differences:
 * 5) **Woody prioritizes the well-being of his owner Andy and the other toys while Losto grows to hate his owner Daisy and children in general and treats other toys horribly.
 * 6) Marvel Comicsː Spider-Man and Venom
 * 7) *Similarities:
 * 8) **Both are humans that have spider-themed powers, a secret identity, and worked at the same place
 * 9) *Differences:
 * 10) **Spider-Man is a hero who helps save his family, his friends, the people of his city as well as the entire world, while Venom is a ruthless killer who treats people horribly, and kills them.

The Overall Reason Why The Trope Isn't So Different

 * 1) It highlights what the two characters have in common and how they are different from each other.