As the University of North Carolina at Chapel Hill points out, instructors often assign comparison/contrast essays because such writing requires students to analyze objects or concepts and explain the similarities or differences between them. For example, an essay might examine how high school is like -- and not like -- college or how the causes of World War I and II were different and similar. The thesis for a comparison/contrast essay explains the essay's purpose and organization in one concise sentence.
Examine the Assignment
The thesis establishes the main point of the essay. Does the assignment ask you to compare, contrast or both? A thesis asking you to compare or contrast might read, "The newest version of the game differs from the older game in terms of characters, technical specifications and price." However, for a comparison and contrast, the thesis could be "Although both use the same story line and offer similar game play, the newest version of the game differs from the older game in terms of characters, technical specifications and price," indicating the essay will cover both similarities and differences. If the assignment requires you to argue a position, indicate your position with a thesis like "Although the newest version of the game differs from the older game in terms of characters, technical specifications and price, the older version is much more popular with users."
Select a Topic
After determining the assignment requirements, come up with a topic that fits and creates an interesting essay you can set up in your thesis. Rather than discussing obvious similarities and differences, an effective comparison/contrast explains ideas not readily apparent. For instance, looking at the similarities between two brands of shoes may not be the best topic if such comparisons are easy to see. A more effective topic choice could result in a thesis such as "American and European soccer differ in equipment, scoring and penalties." Although both games are considered soccer, this paper will cover the contrasts.
Create the Thesis
Put your points together to create a thesis for your comparison/contrast essay. The main part of the thesis should explain the importance of the similarities or differences in the paper. Such a paper could argue that one political candidate makes a better choice than another or that viewers will find an original movie more entertaining than a remake. The thesis reflects the attitude that the main body of the essay will convey, so write a thesis you feel you can support with details in the essay.
Refine the Thesis
List the specific points you will compare or contrast in the order they will appear in the body. This structure gives the reader a map of your essay, either in a block format or point by point. Block format covers each object in an individual paragraph, while point by point covers each similarity or difference. For example, for the thesis "The Morkie makes a better pet for kids than a pure Yorkshire because of its loving attitude, playful personality and easy care," the body could have one paragraph for the Morkie discussing all these concepts followed by a paragraph about the purebred. The point-by-point organization would have one body paragraph talking about the loving attitude of the Morkie and how it contrasts with the purebred followed by one about the personalities and then one for the care. The thesis sets up the order of ideas.