Damn, work had me offline for a long time.
Well, Fallen Angels traditionally are Angels who deny God, and fully acknowledge they did it to themselves. Doesn't matter if they lie about it, they did it, and depending on the Judeochristian sect, they can come back to God by apologizing. God, of course, forgives them-as long as they truly understand and regret their crimes. In some sects, God says, "fuck you, you understood my love and threw it away. I only reserve my forgiveness for humans."
In this world, that's not the case. God is freedom here. Fallen Angels are Angels who discovered that anarchy is not all it's cracked up to be, and order can be useful. Understanding that, they may decide to leave God. In that case, their wings and halo glow red like demon tails and wing, and their weapons glow black with hints of yellow. They are then kicked out of Heaven.
Demons, traditionally, never got the chance to Rise. As far as I've researched, there has never been an official case of a Risen Demon. In fact, a good bit of the older books claim that there are no demons, only fallen angels, Lucifer's old buddies from Heaven who fell with him. Some unorthodox groups-- like some Unitarian friends I have--believe that demons can Rise, as God is all-forgiving and all-loving.
Not in this world. Risen Demons may be accepted by angels as an ally, but they and fallen angels will never be fully accepted by God or Satan. Of course, they always have the chance to Rise or Fall back to their old Grace. Risen demons are still red or blue-grey colored, but their tails, wings, and weapons now glow blue with white accents.
In a way, Fallen Angels and Risen Demons simply realize that such polarization is retarded, and that humans have it better. Although, there may be some who switch entirely to the other pole, but they be high to think that's a good idea. Word. Yo. Fo'shizzle.