Corns and Rats are very closely related, and are both part of the Elaphe species
This has pretty much been established already. The question now is, what makes a cornsnake a ratsnake? Its not just because someone a hundred years ago said so.


don't know much about Kings but I do know that they are quite different in range and in species. That's the species difference between them
Hmm...not really, no. Members of both groups (Pantherophis and Lampropeltis)can be found in the same environments and even the same species (split into subspecies) can be found in different environments. For example, the cornsnake and the Great Plains ratsnake are technically the same species, yet found in very different habitats and ranges.

There's more to determining these things than just range and behavior.