Kindly engage your sense of humour.............
Dark blue means they are over deep water
Light blue means they are over shallow water
Green means they are over grass
White means they are over snow or concrete
Purple means they are purplexed
Dark brown means they are in deep you know what
There's a genuine explanation of BOTH colours at the bottom of the page (not this page)
Meanwhile have fun
If you are still on default colors than red planes have ADS-B, (don't ask) which is part of the next gen control system. The orange planes have the older mode C/S transponders. We will all be ADS-B in 2020. You can change the color of the planes but only the ADS-B planes. Orange planes are on a flight plan and positions are not as accurate.