The purpose of a narrative report is to describe something. Many students write narrative reports thinking that these are college essays or papers. While the information in these reports is basic to other forms of writing, narrative reports lack the "higher order thinking" that essays require. Thus narrative reports do not, as a rule, yield high grades for many college courses. A basic example of a narrative report is a "book report" that outlines a book; it includes the characters, their actions, possibly the plot, and, perhaps, some scenes. That is, it is a description of "what happens in the book." But this leaves out an awful lot.
There are no hard and fast rules about organizing a comparison/contrast paper, of course. Just be sure that your reader can easily tell what’s going on! Be aware, too, of the placement of your different points. If you are writing a comparison/contrast in service of an argument, keep in mind that the last point you make is the one you are leaving your reader with. For example, if I am trying to argue that Amante is better than Pepper’s, I should end with a contrast that leaves Amante sounding good, rather than with a point of comparison that I have to admit makes Pepper’s look better. If you’ve decided that the differences between the items you’re comparing/contrasting are most important, you’ll want to end with the differences—and vice versa, if the similarities seem most important to you.