A couple months back at Google I/O, Google introduced a new feature called smart app updates. This feature is designed to speed up updates for any app within Google Play. Recently, Android Police along with individual Android users have confirmed that Google has enabled smart app updates on its Android platform.
Smart app updates is a really great feature to have. Instead of being required to re-download an entire app (or in our case a full game) whenever an update hits, we’ll now only have to download the portion of the app that is new. A commonly used example of this is the new Instagram 3.0 update that was released yesterday. Instagram is a 13MB app, but only about 3MB needs to be downloaded before installation begins.
Expect to spend a lot less time and data downloading Android app updates from this point on.
Via [Android Police]