Ah ... in the golden olden days when you hang a lantern at the bow for anchoring! That seems like language from the olden days that appears to carry forward. Makes no difference as long as you know what you've got!Bow light is a little more obscure, but frequently mention, "boat at anchor" and " visible 360 degrees." One article even mentioned that sailboat people think masthead means the sail's mast but is referring to the light mast used for it on a powerboat.
If you have any reference that contradict these definitions, I'd be happy to see them.