Basically @cooldan the LCD 'ColorDMD' uses a PC monitor initially- these are classed as LCD. The ones like the Pin2DMD (the ones the ColourDMD LED one is based) uses single RGB LEDs in the same layout as the original DMD installed in the game.
The LED version is also the same physical size as a normal DMD - the LCD one is bigger and overhangs over the top of the speaker board on most games.