4K resolution
So while 4K UHD sounds like it has a pixel structures with 1/4 the area of 1080p, that does not happen with pixel shifting. Only a true 4K projector offers that level of resolution. That's why "true" 4K projectors cost so much more than 4K UHD projectors with otherwise similar feature sets. They produce smaller pixels, finer resolution, no compromising of detail or color from overlapping pixels. By comparison, the slight difference in aspect ratio between DCI and 3840×2160 pixel displays without overlap is insignificant relative to the amount of detail.
Apple TV
The 1st and 2nd generation Apple TV video output can be set to either 1080i or 1080p; however, this resolution is limited to the user interface and the viewing of photographs – all other content is simply upscaled to those resolutions. Those models cannot play 1080i or 1080p video content (e.g., HD camera video). The 3rd and 4th generation Apple TV support 1080p video content. The Apple TV 4K, as the name suggests, supports 4K resolutions and HDR, including Dolby Vision. 4K content from sources such as iTunes can be played on a compatible 4K television set.