“Android Marshmallow 6.0” is Google’s successor to “Android Lollipop”. This new operating system (OS) for Sony’s Android TV features:
1. A revamped Home screen; re-organising the apps and input shelves
2. The ability to use a USB or hard disk drive as additional memory to store apps /games/etc
3. An improved and more intuitive help menu called “Smart Help”
4. And other user interface (UI) and performance improvements
main important feature is to use USB stick or hard disk drive (HDD) as expandable memory: move apps / games to USB stick or HDDs: Easily transfer apps and games to portable storage devices.
source info here