>>712730645
yellow composited the video into a single signal, the ones with more, component separated the video into luminence and 2 color difference signals for red and blue to give you a cleaner picture closer to RGB and allowed for higher resolution and progressive scan.
this isn't always wanted though, retro games sometimes look better on the shittier composite video signal, because of the dithering blending the colors together. like the sonic waterfall as a famous example