Imac retina 4k 215 inch 2017 displays have a 4096 by 2304 native resolution with support for one billion colors.

Is retina better than 4k resolution. Apples retina diplay imacs all have 220 ppi for their 4k 5k and 6k displays but you will probably be happier with a heavier wallet an a nice dell 4k 5k or even 8k display instead. The 97 inch ipad pro has a 97 inch display measured diagonally with a 2048 x 1536 resolution. 4k is just a total pixel count and a 4k display can be either better or worse than retina resolution standard depending on whether the viewing distance is more than or less than 15 times the picture height.

Macbook retina 12 inch early 2015 and later displays have a 2304 by 1440 resolution at 226 pixels per inch with support for millions of colors. This gives it a ppi of 264 which apple considers enough to be a retina display for a tablet. As for why the chinese havent copied it apple displays do have very tight tolerances sometimes tighter than the normal manufacturer and are nicely calibrated.