It can be tricky. The differences when young are minor so depending on size/maturity it could be very hard. As they get older it becomes easier. It's more obvious when you have a group of them to compare against eachother.
Males- higher dorsal fin , head more arrow/wedge shaped and larger in proportion to the body . Both fin and head shape are in comparison to the body & ratios can be thrown off if the fish is over weight.
Females - are heavier bodied fish , the have a rounder head that is more proportionate to the body. Fins also are not as tall .
If you search the forum I have a post here somewhere on sexing Auranti with pics. The colors won't be the same but the the shapes your looking for are.