Hopefully this will help:
micro zoanthids- the smallest of the smallest zoanthids
Zoanthids- as the title states they are zoanthids but to give a size reference they are items such as your hornets, fire and ice, yellow jackets and so on.
Palys- AKA Zoanthus Gigantus Things that fall into this group are most PE ( People Eaters) magicians, blue agave, rainbow palys, pink hippos, and so on
Protopalys- reference for this type, Nuke Greens, Purple Death, Captian America, Mind Blowing
I hope this clears up some of the difference in why some are called zoas, others palys, and proto palys.
Often times the protopalys and palys get mixed up but if you put a nuke green next to a magician you can see the obvious difference in appearance