2k and 4k are resolutions, which refer to the total number of pixels on the screen. Of course, the more pixels, the clearer. However, they should also match the size of the TV and the distance from watching TV
In fact, the current TV signal is generally HD, which is 720p (1366 × 768). It is clear enough below 40 inches
TVs larger than 40 inches generally use FHD (1920 × 1080), and the 2k resolution advertised by the manufacturer is actually this resolution
4k is the future trend (3840 × 2160), but now there is no video source, so it is a bit flashy
