Comparison diagrams allow you to compare the response times of several test runs.
This is commonly used to visualize tuning efforts; that is, "before and after" tuning of the webserver. In contrast, to load curve diagrams, these comparisons of test runs can be made with the same number of users; however, this is not mandatory. You can compare any test runs as long as all test runs have used the same name for the web pages (same text for all page break comments).