Compare vs. Contrast

Some people are under the impression that comparison involves only similarities and that the word contrast must be used to refer to differences. In fact, one meaning of compare is “to note the similarities and differences between two things.” Thus, the expression “compare and contrast” is technically redundant (though so commonly used that it is not considered incorrect); teachers use it in order to emphasize that they want you to discuss both similarities and differences.

Note that compare can be used with either with or to (see this page for more information); as a verb, contrast should be used with the preposition with:

compare one thing to/with another thing

contrast one thing to another thing
contrast one thing with another thing

However, as a noun, contrast can be used with either with or to, as in the expressions “in contrast with” and “in contrast to.”