You can see what changesets have been submitted to the server but have not been downloaded into the workspace within the Submitted Changesets. The changesets which have not been downloaded will appear with a different icon, as described in the section called “Submitted Changesets”.
There are times when it is useful to see the actual file differences since you last updated your workspace. You can achieve this with the 'View Outstanding Changes' operation. Right-click the workspace in the top left pane of the Workspace View and select the 'All Tasks | View Outstanding Changes' menu. Alternatively you can select the 'View Outstanding Changes' button in the Workspaces View. This will launch the Stream Compare dialog.