Use maintenance mode to update or correct test object properties in the object repository. If you run a script in maintenance mode and it encounters a problem where the object cannot be identified in the application, the Maintenance Run Wizard will open and help you identify the object.
Update run mode will update test object descriptions, checkpoints, output values and Active Screen captures.
For more detailed information, check the UFT User Guide under
UFT User Guide > GUI Testing Design > Maintaining and Updating GUI Tests or Components > Concepts > Maintenance Run Mode
and
UFT User Guide > GUI Testing Design > Maintaining and Updating GUI Tests or Components > Concepts > Update Run Mode.