In all hawks, the female is larger and more powerful than the male. 
Hawks are divided by falconers all over the world into two great classes. 
The first class comprises falcons, longwinged hawks, or hawks of the lure, distinguished by Eastern falconers as "dark-eyed hawks." In these the wings are pointed, the second feather in the wing is the longest, and the iris is of a deep, dark-brown hue. Merlins must, however, be excepted; and here it would seem that the Eastern distinction is the better, for though merlins are much more falcons than they are hawks, they differ from falcons in having the third feather in the wing the longest, while they are certainly dark-eyed hawks.

The second class is that of hawks, short-winged hawks, or hawks of the fist, called by Eastern falconers yellow eyed hawks. In these the wings are rounded, the fourth feather is the longest in the wing, and the iris is yellow, orange or deep-orange.