All game systems outputs 480i. Its 640x480 pixels, interlaced.
Simple RF cables are the worst quality, with all signals going through the same "pipe".
Composit cables (red/white/yellow "rca") split the audio into two seperate cable (left and right) and the video into its own cable (yellow). Sound is greatly improved, video is improved as well, but not perfect.
S-Video divides the video information into two separate signals: one for color (chrominance), and the other for brightness (luminance). The audio is the typical red/white stereo cable.
Component uses 3 cables for the video. Red/Green/Blue. The Green cable contains brightness (luminance). The Blue and Red cables contain the color (chrominance) information. Its taking S-Video another step further.
All of these produce "480i".
Component however, can also support 480p (640x480 progressive), 720p (1280x720 progressive) and 1080i (1920x1080 interlaced). There is absolutly no support for this with the Neo Geo hardware BTW.
Interlaced mean it draws all the odd horizontal lines in one pass, then all the even ones in the next pass. Progressive draws all of the lines in one pass. So 480p has twice as much information on the screen at a time than 480i. Thats why DVDs look twice as good on an HDTV, twice as much info is displayed at any given moment. Same with most Xbox games on an HDTV.
Hope this answers more questions than it raises.
note: The Neo-Geo was never meant to do any better than 480i, so in the US at least, S-Video is pretty much as good as it can get (and it looks fantastic BTW).
also note: since the Neo Geo came from the factory with S-Video output, it likely looks superior to a modded AES system. A computer can likely make far better soddering (?) joints than a shakey hand and a $3 wood burner.
edit: correct the explaination of Component.