Comparison.

An instruction or command that compares two values.

Illustration by comparison; simile.

To assess the similarities and differences between two or more things ["to compare X with Y"]. Having made the comparison of X with Y, one might have found it similar to Y or different from Y.

“Compare the tiger's coloration with that of the zebra.”

To declare two things to be similar in some respect ["to compare X to Y"].

“Astronomers have compared comets to dirty snowballs.”

(grammar) To form the three degrees of comparison of (an adjective).

“We compare "good" as "good", "better", "best".”