A desktop/workspace pager aids in working with more than one workspace. By displaying workspaces in a small view and allowing to drag windows in this view. A pager is not required when working with multiple workspaces, managing workspaces is done by the windowmanager, the workspace name and contents can be seen in the toolbar and windows can be sent to other workspaces from the window menu or configured in the apps file.

But pagers give a better overview, some show only window borders, others pictures of window contents or icons of the running application.