We are seeing a variety of video resolutions hitting the market with the advancement of new video capture and playback technologies . Here is a diagram that visually compares the different sizes of these video formats: 4K 4096×2304, TW HD 3840×720, TW SD 2400×600, HD 1080 1920×1080, HD 720 1280×720 and SD 640×640.
Click for larger preview.
Here is an alternative diagram with slightly different video formats: 4K 4096×2304, HD 1080 1920×1080, TW 1920×480, DW 1280×480 and SD 640×640.