Hairy Woodpeckers eat wood-boring insects, seeds and berries. And like all woodpeckers, they have nostril bristles that act as filters from all the sawdust they create.
Hairy and Downy Woodpeckers look very similar. View a side-by-side comparison of them. Notice how much larger the bill of the Hairy Woodpecker is compared to the Downy Woodpecker. Besides using their bills for comparison, remember that Hairy Woodpeckers prefers trees and trunks while the smaller Downy Woodpecker prefers small shrubs and small branches.