Downy Woodpecker

Downy Woodpecker (6 3/4") tall, which is the size of the suet feeder he's on. Hairy Woodpeckers are (9 1/4") tall, which would probably place him hanging off the bottom of the feeder by 3 or so inches. Unless you have a larger than typical suet feeder. The two birds look identical, have the same range practically.

But, something I'm not good enough to tell yet - is the Downy Woodpecker has a bill that is "1/2 the depth of the head". While the Hairy Woodpecker has a much larger beak to head ration that is "more than 1/2 the depth of the head". In my bird book, Stokes Field Guide, the birds look identical but for the beak on the Hairy being nearly the size of the head.