Difference between Updated Run Mode & Maintenance Run Mode?

Update Run mode updates all properties of objects and checkpoints in case of failures. So if a object gets recognized using SMart identification then correct properties are updated in the OR. In case expected and actual values of checkpoints are different then they are updated as per the actuals.It can be selected from Automation -> Update Run mode

Maintenance run mode is used when you want to update objects which are failing during execution. So if the object cannot be recognized at all with current settings instead of giving an error QTP will give a dialog to point the object to a new object if required.