There has been a minor behind-the-scenes update to the Google Play Store that some users are seeing. If you go to the Top Charts in the Store, some users are now seeing a “Show installed apps” toggle at the top of each page. Enabling this allows you to either display or hide the apps from that chart that you already have installed. The idea is to speed things up a bit by not having to wade through apps you already have installed. You can simply hide them and see the other top apps you don’t have installed.
There is nothing that you need to do necessarily to get the update. It will just appear for you once it hits your account.
The update appears to be part of a larger effort by Google to improve the overall layout of the Top Charts within the Play Store. The charts appear much more adherent to the Material Design rules.
It also appears that this new toggle is available on all of the Top Charts. If you aren’t familiar with these charts, they show you things like to the Top Free apps, Top Free Games, Top Grossing apps and so forth. It is a quick and easy way to see what other Android users are playing or using to see if it could be fun or useful for you.