Here is a depiction of male and female Geophagus pellegrini. As you can see the male is very colorful with pointed fins. The dominant male in the tank has darker red coloration and a slightly larger nuchal hump which can grow very pronounced with age and presence of other males. The females in comparison are rather drab and do not have pointed fins.
I should also add that this variant comes from the Rio Atrato. There are also collections from the Rio San Juan which seem to have less red and the lips may lack the blue seen in those collected from the Rio Atrato. Once mine grow out, I can add my observations from them.