QHD or Quad-HD is actually 2560x1440 (4x qHD, quarter high definition, 960x540). UHD is 3840x2160 (or UHD-1 if you prefer). But everyone seems to be confused about who's saying what these days. However it seems they're underselling this spec, as 3440x1440 is above QHD but maybe because it's not UHD they have to call it QHD? ROFL. Jeez, I just confused myself reading that...
This crap is really a mess these days.
4K is 4096×2160, which is funny because most Tv's/monitors are saying this but are really UHD...LOL. You'd think someone would buy one then sue saying hey, 3840x2160 isn't 4K, and it also has to do with encoding (rates, quality & color depth) not just that pixel# so lying two ways when doing this kind of and they KNOW it. Maybe lawyers are too stupid/ignorant to start the lawsuit?