2K and 4K refer to different monitor resolutions. 2K or Quad High-Definition (QHD) has a resolution of 2560 x 1440 pixels, and it’s called 2K because its horizontal resolution is roughly 2000 pixels. 4K or Ultra High-Definition (UHD) has a resolution of 3840 x 2160 pixels, and it’s called 4K because its horizontal resolution is roughly 4000 pixels. 4K is the better choice for a powerful and modern gaming rig because they have more pixels and sharper image quality. However, the difference isn’t noticeable on smaller screens or at typical viewing distances. 2K monitors are still popular because they balance performance and resolution.