Thanks, Meadowlark!!
The males breast or belly area has subtle variations on the bronze/red color and the female has variations in the gold/yellow range. The males "ear tab" or flap is longer anterior/posterior or front to back than the female's is. In other words, the front to back length is about the same as top to bottom. The females ear tab is more of a slit or crescent without a lot of front to back length. Wish I could draw a picture here.
The male also has a more pronounced hump right in front of the spiny dorsal fin, especially dominant males.
Keep in mind that some male bluegill will intentionally mimic female patterns but females will not mimic male patterns. The two male variations are "cuckholder" and "sneaker". The former will hang around the nest trying to look like a female, then dart in at the prime moment and distribute sperm. The latter remains small and without much color and literally hides in the bushes for a chance to charge in for one good spurt. Strange happenings......
