Lol, good one. Well usually there's a difference in color morph too because they often occupy different niches or are from different seas. The real reward of scoring a micro comes when one lets it grow out.
Micromussa is kinda of like a mix between an acan and a favia. The growth pattern is more like a favia but it has that velvety texture like an acan. Also micromussa in most cases will be bluish in color where acan lords come in more diverse color morphs.