From what I have learned... it's all in the eyes. An Occellaris clowns black part of the eye (or pupil) is bigger and just outside the pupil the color is darker usually than the color on the forehead area of the fish. On the A. Percula, the color just outside the pupil is usually brighter and matches the color on the fishes forehead area almost perfectly. Also on the A. Percula I have noticed that the pupil area of the eye is much smaller. I will post some pics to show the difference. Pics coming up in about 15 minutes
A. Percula - Notice the eye area

another A. percula
Anyone, support or debunk these theories? I was actually told about this by a clown breeder in Seattle.... Thanks Inwall for that connection!
GLTA
Now- Here's the A. Occellaris