What is the relationship of Responsibilities to Roles

We have been using the classic responsibility setup in our organization for many years. Recently, we began to experiment with utilizing roles through the User Management functionality. We have several responsibilities that all use the same menus - this includes low level and high level users that differ by the exclusions set up in the responsibility - a high level user would have the ability to edita record whereas the low level user is supposed to only view the record. What we have found, is that upon basing our roles on these same responsibilities, the lower level users have most