what is the difference between 4th generation and 4k apple tv?
Whereas the fourth-generation Apple TV maxed out at 1080p video at 60 frames per second, the new 4K model supports a resolution of 3,840 x 2,160. This means you'll get much crisper and smoother video than previously, assuming you have a 4K television. ... Apple is also bringing HDR and Dolby Vision support to the Apple TV.