Google makes two different versions of Android and they`re both equally important
(Android Central)

Android isn`t just what you can see; it`s what powers the things you can see. Did you know Android P uses a trackball for navigation? A trackball! The hardware thing that died with the Nexus One and HTC Hero because everyone hated it. Well, it does. It also uses a joystick, a keyboard, a gyroscope, gestures, and a back button. And probably anything a developer can dream up that will hook into the user input APIs that are part of Android P. But none of that means your next phone will have a trackball or a keyboard, or that you won`t have a back button in your navigation bar. It only means that you could. We see this on the Android P beta builds that have been made available for various phones. The back button on the home screen is gone most of the time and new native gestures have picked up the slack. And there are other changes as well, like weird quick settings and a colorful mess look to the interface all-round. And collectively, we`re not connecting with Android P because of th...