You can view and compare the differences between an item revision and its ancestor.
To compare an item revision with its ancestor:
Do one of the following:
Web client
Select an annotation and on the toolbar click Compare. The Show Differences dialog box appears. For details see Comparing Item Revisions and Files.
Desktop client and Windows Explorer integration
Right-click an annotation and select Compare with <change request ID>. The item revisions are opened in the default merge tool.