What are white peacocks?

White peacocks, or peafowl, are regular peacfowl, but with a gene mutation in PMEL17 which means melanin can't get into their feathers, making them white! There are also piebald peafowl, who have a different mutation than full white peafowl.

Contrary to popular belief, they are actually albinos. The mechanism for leucism and albinism are completely different, and the mechanism that makes "leucistic" peacocks white is an incomplete form of albinism.

TL;DR: They are just albino versions of regular peafowl.