i havent seen a red pad before. I only have the yellow, orange, white, black and blue. black is for applying waxes and sealants. The blue pad applies paint glaze in an ultra thin, even coat. It can be used to apply wax, also. If i do a whole detail and use all 5 pads and finish off with the blue pad, the surface is smooth as glass.
If anyone is interested in buffers, this is my setup. If you have never used a circular polisher, i would not suggest buying one. If you dont know what you are doing it is very easy to burn through the paint.
This is the pad kit i got
http://www.autogeek.net/curvededge.html
And this is the circular buffer i have
http://www.autogeek.net/dw849.html