Haha! Idk what i was thinking I have a khaki campbell, Lol! But I have never heard that the males can have green heads. It might be that way seeing as though I only have a female. Pics would be a lot more help in telling what you have.
The quack, females will have a loud quack while the males have more of a raspy quack. Also if they are old enough the drakes will have few feathers at the base of his tale that curl, females will have straight tails.