Tht larger of the two( the one on the bottom in the last pic ) it has an arrow shaped head usually a sign of a male the other one ( with the circular pattern in the middle of the back ) has more of a tear drop head usually a sign of female . I am no expert but that is what I can pick up right off the bat.
I think yhey are still too young to tel for sure but the head is a good indacator power feed on gut loaded crickets , mealies, and a few wax worms and they will be their in no time.
One is feeding very well on mealworms and now crickets. The other doesn't touch mealworms and only ate about 3 small crickets today. Yesterday, he'd strike and he get them in his mouth, but then he'd spit them out...
Is there anything i can do? Is he just going to let himself starve to death?
If it becomes a problem you might have the bigger one picking on the smaller one and not allowing to eat. This can be a problem with leos being kept together. Watch them while they eat, otherwise you can separate them during feeding time.