The Hairy Woodpecker is similar to the Downy Woodpecker. The Hairy Woodpecker excavates tree trunks for insects, rather than tree limbs. The Hairy Woodpecker is slightly larger than the Downy Woodpecker.
The bill of the Hairy Woodpecker is at least as long as its head, while the bill of the Downy Woodpecker is only half as long as its head.