The three-toed woodpecker gets its name because it is one of the only woodpecker species that has three toes on each foot instead of four. Other then the two varieties of three-toed only the black-backed woodpecker has three toes. The black-backed are also found in boreal forests, although they do not breed quite as far north. The black-backed is very similar in appearance to three-toed except as its name would suggest it has a black back where the three-toed woodpecker's back is mottled black and white. The top photo in the post is a three-toed where the second is a black back. As you can see they look very similar. These are both males which you can tell by the yellow crown on the top of their heads. The female three-toed woodpecker has a mottled black and white crown where the top of the female black-back's head is all black.