The core of a comparative essay is having two subjects or categories that can be examined and evaluated. You must choose two singular subjects, such as cats and dogs, or you can choose categories of groups of subjects, such as when comparing Democrats and Republicans. Important to the essay is that your subjects will not just be examined individually but will be set against the other in contrast. When you choose your subjects, keep in mind that they cannot be so similar that well-defined contrasts are not possible. For example, a poor choice would be "tomatoes" without defining differences by specifying "roma tomatoes" and "big boy tomatoes."
As you choose your essay subject matter, you should have in mind an idea of comparison and contrast that will fit your subjects. Before writing a paper, you will have completed some form of research about the topics and with this you will have formed an opinion about their relationship. This opinion will be presented as a thesis statement in the introduction of your essay. The thesis generally states your expected findings and draws the reader's attention to what you will be writing. For example, "Roma tomatoes enhance salads while big boy tomatoes slice well for burgers and grilled sandwiches."
From the thesis statement you will present your supportive research. One of two methods is acceptable for presenting your information. You can create paragraphs that individually introduce the reader to each subject. The next paragraphs are formed to compare the two, with more paragraphs drawing out the contrasts. A second method combines the subjects to introduce and show similarities. This is followed by an extended focus on the contrasts. The first method is best if your subjects are complex or widely misunderstood and will benefit from an extensive explanation of characteristics. Technical essays often employ this method.
Keeping your original thesis statement in mind, your concluding paragraphs should wrap up the information you have presented. This information should be summarized briefly and the strongest points that support your position must be highlighted here. The conclusion serves to remind the reader of your position and demonstrates that you have fulfilled the initial promise. Conclude by re-stating the thesis in a strong, assertive voice, adding supportive points. For example, "Due to their size, roma tomatoes have a great deal of convenience and are best in salads, but big boy tomatoes slice well and are the better choice for burgers and grilled sandwiches."