I was thinking that they may be male and female but the one in the second picture that i think is female has grown twice as fast as the one in the first picture. The second one is very greedy though and is one of the first fish at the top of the tank waiting for me to drop in food.
The only reason i thought they were differant sexes is the body shape. The second one is so much deeper bodied than the one in the first picture. I'll try and get a picture of them together so that you can see the differance.
The one in the first picture seems to have larger but less spangles over its body too.