Here are five of the most common in my area of Oklahoma. I will try to give you some clues as to which is which and how to tell. Think size, tail shape, head shape and then coloring.
Buteos: These are large, stocky birds with broad wings and wide rounded tails.
Ferruginous Hawk: The largest of the Buteos, measuring 22' to 27' in length, having a wingspan of 4 to 5 ft. They have either a light or dark morph. They hunt in open prairie, like Red-Tails and will take food from other birds if they choose to, since they are larger.
Legs are fully feathered, in the same rough mottle as the belly. Light banding across width of tail and dark 'commas' at edge of dark coloring on tops of wings in flight. They fly with slow, smooth wingbeats and soar with wings either in slight V or flat. They are often mistaken for small eagles due to their size.
Red Tailed Hawk: This guy is fairly easy because of the reddish brown tail in the adult. You can see the red even when they are in flight and the body has the whitish, streaked with reddish brown chest and belly. Red-Tails love the edges of woods, roadways, plains, sit on fenceposts along highways as well as high in the bare trees of the winter landscape.
Rough -Legged Hawk: Similar in size to the Red-Tailed Hawk but wings and tail are longer. This bird is native to the Arctic and winters in our area. When in flight it will look whiter underneath with a blotched belly and two dark spots at 'wrist' as well as dark outlining of wing edges and tail. Rough-Legged Hawks are one of the few raptors that hover on beating wings as they hunt. They get their name from the fact that their legs are feathered all the way to their toes, one of only a handful of hawks whose legs are not bare.
Accipiters are smaller than Buteos, have shorter, rounded wings and longer, straighter tails. They prefer to hunt in forests and thickets because they are able to make quick, sharp turns. Our two most common are:
Cooper's Hawk ((10' to 14') Sharp-Shinned Hawk (14'-20')
These two are pictured side by side so the differences are easily seen. They are both smaller hawks, having short wings and long tails for speed and maneuverability. Sharp-Shinned hawks prefer more urban areas most of the time and Cooper's Hawks prefer the open prairie. You can see that the chest barring is very different; Sharp-Shinned Hawks are a dark grey on the backs and they have a smaller head, although overall they are larger than the Cooper's Hawk.