Well, through experience you kind of get a feel of what morphs come from different locales around the world.
Usually, and I'm sure there are exceptions, Caribbeans tend to not be availlable on what we are used to calling rock....as harvesting of rock is illegal here....though in Haiti it's fine, so you may find some Carbbeans from there on larger rock. Usually if you see something at a vendor labels "seamat"...its a good indication it's of Caribbean origin....as all the wholesalers here call them "green sea mat". They might be the brightest Pepsi can blue, but they call them green
Usually as well, Caribbean zoanthids are much "stickier" than Pacific zoanthid colonies. I can place my hand flat down onto frags and pick them up. I've never had a Pacific show that characteristic, though even some of the morphs down in the Keys lack this stickiness.
Other than morph, known location of seller, and probably a few more things I'll think of later, it's tough to differentiate.
Bout all I can say right now, Larry's worked with them almost as long as me, so he may have some more insight also.
Peace, Bryan
ps-quick little edit - Most of the time Caribbeans won't stretch for light like Pacific zoas, they just close up and eventually die. Most Tongans, Solomans, what have you, will trumpet up if placed on the bottom of a moderately lit tank...I've yet to see Caribbeans do that.
i believe alien eyes are carribean, as well as the cat's eyes. iirc, they tend to be a bit larger, and a lot of them have a contrasting circle in the middle of the polyp
I was thinking they had some sort of slightly different appearance in the oral disc. It seems smoother or something, but I could just be imagining things. It's likley that the smoother look is found in other regions, too, but I just may not see them. I've never done wholesale, so that limits my experience.