What is the difference between restoring and installing an app on an Android device? Is there any difference between restoring an app and installing an app on an Android device, or are both the same?
Well, one that comes to mind - if application is removed from market or is not listed as compatible for your device, restoring from Google account is one way of getting those applications. I did it with "FML official" and "Amazon" applications when they were not available on Nexus 7 2013 - "backed" them up on my Samsung S2 and "restored" on Nexus 7.

And, of course, for some applications settings are restored too.