The guy that named them? Lol, not much, they just look a little different.
IME poker star has orange polyps but only a the very edge, and the polyps get very green, pretty quick, it almost just looks like a purple monti with green polyps, rainbows have more orange, and take a long time to start yellowing and eventually turn green.
Kris's pokerstar is different, I am not sure which or what it is as it completely encrusted some kind of tube worm, or other SPS, so if he frags it up a bunch it may never branch again.