How long have you had this fish? My boy looked like yours when I first go him about 3 months ago and is now completely dark blue... Expect a lot of changes. His head was light like your boys' and now it is a dark, dark orange, almost black. He had white everywhere, and now all that is left is a stubborn little bit of white on his anal fin that I hope will disappear in a few weeks. I would not be surprised if he is a marble.
As for the tail, that can also change a lot. My boy was a delta when I bought him, but now he is almost halfmoon...
Here is a thread I had a while back about his changes. He has, of course, changed since these were taken, but they are the most recent I have posted here. I guess my boy had more blue to start, but your boy will probably still change a ton. And just look at that tail!