Apple TV 3rd Generation – Apple Community – AppleTV 4 Jailbreak (appletv4jailbreak.com)

‘App’ availability on Apple TV (3rd generation) is fixed per country or region. Users can show or hide icons, but not add to it.
Apple TV (4th generation) introduced an on-device App Store, to install user choice apps. This made thousands of apps available for that platform. The App Store is not available on earlier models.
Some apps on iOS devices allow their content to be streamed through AirPlay to an Apple TV (3rd generation), at the app developer’s discretion.