Set up a system for recording the characteristics of each literary genre. One option is the Venn diagram, which consists of two large circles drawn so they overlap creating a shared space. Another option is to make a three-column chart with one column for each type of literature and one for shared characteristics. Each of these methods gives you a way to sort out the data belonging only to the first category, that belonging only to the second category and that belonging to both.
If using a Venn Diagram to sort your collected information, label the first circle "Romanticism" and the second "Colonial Literature." Label the space where the circles overlap "Shared Characteristics." Reserve the outer area of the first circle for details that are true only of Romanticism and the outer area of the second circle for items only true of Colonial literature. The shared space is for aspects true of both. If you choose to create a three-column chart, use the same labels as the Venn Diagram, designating the center column as the shared space.
Read descriptions and examples of each literary type. As you read, make notes on your recording form to clearly show where the pertinent details about each literary style overlap versus where they do not. For example, authors of Colonial literature all lived in the United States, so you would note that fact in the space designated for that genre. However, Romanticism originated in Europe, so you would note that fact in the space reserved for the Romantic style. But the fact that both European and Colonial authors wrote in the Romantic style would go in the shared space.
Make a clean copy of your compare-and-contrast chart for your instructor. You can write it neatly or create it on a computer. If you do it by hand, use a compass to draw similarly sized circles for a Venn Diagram, or use a ruler to make sure the lines of your three-column chart are straight. Write an essay that details your findings, explaining comparisons (similarities) first, followed by contrasting aspects (differences). Use the specifics you wrote in your diagram to support your claims and cite your sources appropriately.