I could've sworn I read in Conscientious Marine Aquarist that the difference between the too is the black, outlining stripe on the white strips; if the fish has them then it's a true perc... if not it's a false
Dont have the book in front of me, so I could be wrong. It could've been that the true percs have THICKER black outlining on their white stripes vs the false which have thinner or none.