So let's say I used Unity and built an app and uploaded it to the android and iOS app store, it is 100 MB and lots of people downloaded it. So now I want to update it to the newer version, however along the way I decided a lot of features were unnecessary so I remove about 50 MB worth of assets and the new build is 50 MB so I uploaded it to the respective app stores.
Will the people who already had my 100 MB app and now update to the new 50 MB version continue to have 100 MB of storage space taken up, even though the new one is half the size or will their app size be reduced to 5 MB according to the new build?
Essentially, how does app store updating work? Is the whole old app deleted and new one downloaded? Are matching files and assets retained and only differences in files and assets deleted or updated? Or are new assets and files just piled on top?
Additionally, for larger games, where the whole game is too big to be allowed on the app store, and where the player has to download more stuff once they have downloaded the game, how does it work? Is the additional, no-longer-needed content left on user's device kept there? Is it automatically removed?