They are considerably larger than a crow, and have a sort of rough look about them. The have a thick bill, and a head that begs for a trim.
The call of the the crow is, of course "caw-caw-caw". When they all get together as a group. like they do around Loring Park, they are called a "murder of crows" Weird. The raven, however has a much more guttural call...almost a loud croaking. There is another, smaller raven that inhabits the plains of West Texas and Oklahoma called the Chihuahuan Raven. He has a tiny patch of white on the nape of his neck. Sometimes you can only see it when he puffs up his head to utter his call "ay chihuahua, ay chihuahua."