It's not always easy to describe the subtle differences between Hairy and Downy Woodpeckers. The larger size and longer bill of the bird on the left shows it's a Hairy Woodpecker. The Hairy's bill is roughly the same length as it's head. The Downy Woodpecker's bill is much shorter in relation to it's head. The red patch on the Hairy shows it is a male and the absence of the patch on the Downy shows it is a female.