yea we try to duplicate but actually come no where close, but fortunetly for us corals are highly adaptable critters. wild caughts are still a must in this hobby. many of the highly desirable corals are only available as wild caughts, and in the beginning of course everything was once a wild caught. yet at the same time most of the best zoas and SPS's (as well as some LPS's, leathers, shrooms, softies, and zenias) you find today are captive breed. captive breed has the huge advantage of being tank proven and already adapted to life in the aquarium so likelyhood of success is far greater. with captive breed though your usually talking smaller frags and a long grow out time till you have a nice colony. personally i have many of both
now on to the dif between zoas and palys well thats a scientific paper in itself. i've resently been informed that my pink pallies that i've had for years are actually Zoanthis gigantus sp. the short answer is something like this true palys uptake sand into their mat (coenenchyme) and zoas don't. there is quite a few discussions on this topic on the RC, and borneman (as well as many others) discusses it a litlle in his book. but the bottom line is they are both in the same family and zoas in the hobby today are most often called by their color form common name then a scientific name