The Sikh turban, like an ordinary hat, can be any colour. It's not an actual requirement, but uncut hair and keeping it clean and tidy, is, hence the turban. There are several 'styles' and men can choose whichever style they prefer. They were traditionally made of silk, which is said to be capable of deflecting a sword blade, it's so strong. I'm not convinced by that one, though.
I'm not sure what name is given to the style that the younger boys wear. Here in Leicester, non-Indic speakers tend to refer to them as top-knots - a small 'bun' on the top of the head, held in place by a piece of cloth resembling a handkerchief.
We once had great difficulty persuading a visiting Russian friend that the young boys in the local morris dancing troop were actually boys and not girls, especially after we'd told her that morris dancing is traditionally a male pursuit. I'm sure she's still convinced we were winding her up.