I'm sure they're on here somewhere... Females tend to be more subdued in coloration, their ear flap is usually yellowish orange. They'll have a bit of a yellowish coloration to the breasts Males, particularly in the spring tend to be black on the bottom fins into their lower half. During peak spawn I have seen some males be almost completely black. Outside of the spawn they're close to females but have a bit more of a orangery as opposed to yellow breast area. Their ear flaps are edged with a darker orange or red, hence the name.

In this link: http://www.tnfish.org/FishIdentificationID_TWRA/TWRA_Sunfish_Identification_Key.htm#redear The top redear is a male, the bottom a female.