There are two general formats for compare and contrast papers:
The Best Way to Write a Compare and Contrast Essay - …
Identify the three subjects that you will compare and state whether you will focus on similarities, differences, or both. The thesis may also indicate which points you will compare / contrast.
101 Compare and Contrast Essay Ideas for Students
Subject by Subject (Whole-to-whole). Your write first about one of your subjects, covering it completely, and then you write about the other, covering it completely. Each subject is addressed in a separate paragraph. The points of comparison or contrast will be the same for each subject and will be presented in the same order.