I think Full HD was really just to separate from 720p. So if you consider "HD" to mean 1080p and UltraHD to mean 4k, its like saying a "Full v6" and a "v8" or

I think Full HD was really just to separate from 720p. So if you consider "HD" to mean 1080p and UltraHD to mean 4k, its like saying a "Full v6" and a "v8" or something. For whatever reason it made just enough sense to never bothered me too much.