"Of course, if you believe Samsung, LG’s new UHD OLED range isn’t really 4K at all, but 3K. Company boffins invited me backstage, to explain why LG’s latest UHD OLED RGBW panel technology, dubbed M+, isn’t actually 4K. According to Samsung, M+ panels are 2880×2160, rather than full 3840×2160. Ergo rubbish."
I have a newsflash for you - none of those are 4K. 3840x2160 is actually called UHD or 2160P. 4K isn't a display standard, but rather a broadcast and film standard. There might be a few "4K" sets out there but the vast majority are UHD (3840x2160).