Saturn has RGB output (as long as you don't have a Hi-Saturn). It does not have color difference output.
Depending on which school of thought you listen to, "component" either means color difference or it means any system that doesn't combine multiple video signals onto one wire (which includes both RGB and color difference). Most references to "component" in American consumer electronics refers to color difference video. Color difference is essentially a specially mangled version of RGB that's convenient for some applications. RGB looks like this:
R: Red level
G: Green level
B: Blue level
While color difference looks like this:
Y: Brightness
R - Y: Red - Brightness
B - Y: Blue - Brightness
This is a little funky. Brightness should be self-explanatory. If you connected only Brightness, you'd get a grayscale image. R - Y and B - Y are the color difference signals. They transmit the difference between their respective colors and the brightness. It turns out that Red, Green and Blue each contribute a precise and consistent proportion of brightness, so it is possible (with the appropriate scaling) to "subtract" one color from the signal and then reconstruct it on the other side of the connection. Basically, the upshot of all this is that a color difference signal can be delivered effectively with less bandwidth than an RGB signal.
In order to convert between RGB and color difference, you need a device called a "transcoder". This basically takes the input signal and performs a type of analog math on each component to derive the output signal. Professional transcoders are expensive, but a simple one is not very expensive to build. You could also build a S-Video -> color difference decoder, but that would defeat the purpose of using the color difference inputs at all.
To me, color difference is a silly input standard. The only thing it's really good for is stuff that decodes MPEG video (which decodes to color difference directly). Just about everything else is converting RGB to color difference so that the TV can convert it back to RGB again.