Hi Mahari,

We recommend using iterations for release/sprint/iteration testing (see the Test Schedule section in the test plan editor).  However, you can use categories, such as Release category or custom categories (preferred over custom naming conventions since categories can be required, enumerations, and used for reporting and sorting/filtering in the table views).  Test plans can be created for different projects using the Product category.  In addition, test plans can be created for different test phases using the Test Phase category.  Note, categories can be used in most test release types.