Board Thread:Speculation House/@comment-24.247.91.107-20140511154823/@comment-26018514-20150222025033

This is the sum total of info I have found on the distinction between a raven and crow that doesn't go into the individual species(of which both have many) in a cursory look:

"A raven is one of several larger-bodied members of the genus Corvus Smaller-bodied species in the genus Corvus include the crows, jackdaws, and the rook."

In other words; same Genus(Corvus), different species.