My understanding with corns is that males have longer tails, but it's not a science, and difficult to tell without better pictures and comparing tail scales.
As mentioned, have a proper vet or reptile guru pop or probe him/her.
If it's for your own edification, I wouldn't even worry about it. Snakes don't care what we call them . I have a blue tongue skink, Frank, and they are difficult to sex, especially when younger. He/she is still Frank.
If you want to breed, again find someone who knows what they are doing and have them show you, or tell you.
As the others have said you will need to have it or popped or probed to be certain, a professional should do this. If you aren't breeding though, the gender isn't a huge deal