1080p means 1080 lines (vertical resolution) and usually means a display which is 1920 pixels wide by 1080 tall. 2160 is double that, and is called "4K" - where the 4000 is now the horizontal resolution instead of the vertical one. Specifically, 2160p is an alternative name for 4K UHD, a resolution supported by UHDTV products and which offers four times the definition of 1080p. The number 2160 stands for a display resolution which has 2160 pixels along the shortest side, while the letter p stands for progressive scan or non-interlaced. In a progressive image, the lines of resolution of the image go from the top of the screen to the bottom. 4K is the direction displays and TVs are headed, but it is still early and there is not much 4K material out there. Hope this helps.