Rock Bass Ambloplites rupestris
http://www.fishbase.org/summary/3361 Warmouth Lepomis gulosus
http://www.fishbase.org/summary/3373 are two different fish.....
They look somewhat the same, but ain't.
Local terminology or local names might mean different fish in different places.
Up here, if you are talking about a "Perch" you most likely are talking about a Yellow Perch.
Down in Tehas, if you talk about a "Perch" (I forget how DD1 spells it) you could be talking about a Northern Bluegill or a Coppernose Bluegill.
