If you went by general looks alone, it can be hard to tell the difference between a Downy Woodpecker and a Hairy Woodpecker.  Side by side it’s easy…on their own, it can be a bit more challenging.  There are some notable differences though.  The Downy is smaller by a good bit.  The tail feathers of the Downy will have some black bars or spots on them, where the Hairy’s tail is unmarked.  The easiest way to tell the difference though is that the Downy’s bill is much shorter.  Shorter than it’s head is when looking from the side.  The Hairy’s bill is as long as it’s head when looking from the side.  Now, you’ll easily be able to tell them apart, unless of course you’re like me and forget…then you’ll have to look it up all over again!