Help with mutation

[bully4t]

Need help with this juvenile Green IRN mutation.
No info about the parents. The thing that bugs me is why does its head looks so much lighter than the other Green IRN. What kind of mutation can do this(cleartail, lacewing,some kind of fallow or just a regular green?). Hope someone can help, as I have no idea. Bird is the one on the left.

[Shempai]

Perhaps this'll help? http://psittacula-world.com/EN/Mutations/P-krameri.htm