Theory:
Update is the version on which all the defects and Enhancements filed in previous version which is fixed in the updated version of the application. Updates are cumulative. Each update will include all fixes and enhancements from previous updates as well. This would mean, for example, that if you have skipped two updates, you could install the third update and still be assured of getting all the fixes and enhancements that were in the previous two updates.
Removing an update - To un-install an update you must un-install the full build of the product. This will in turn un-install all updates.
Installing an update on top of a previous update is permitted. If you have a previous update already installed, just install the latest update directly on top of it.
The “Help > About” dialog will show the version number of the latest installed update.