“UHD features a 16:9 aspect ratio and is twice the resolution of full HD. In other words, two times 1080p, two times 1920 x 1080 pixels, that is 3840 x 2160 pixels. Having the same 16:9 aspect ratio means it is backward compatible with other HD derivates. However, both 4K and UHD can be shortened to 2160p to match the HD standard and therefore, companies use the terms interchangeably.”
“If you think 4K and UHD are one and the same, I don’t blame you. I blame the companies that LOVE to use them interchangeably all the time. You pick up a Blu-Ray movie disc of a 4K movie and you will most definitely see an Ultra HD label on it. 4K is actually not a consumer display and broadcast standard but UHD is. 4K displays are used in professional production and digital cinemas and feature 4096 x 2160 pixels”