I think I have it! I suddenly woke up with this idea. It's just a theory. I think it is the difference between land and nautical terminology. It's whether you're looking at the shape of the land or the shape of the ocean. To someone living on land, who wants to live on it, or add territory to a country, it is a "peninsula." To someone sailing a ship, who wants to know the shape of a coast, it is a "cape." You live on a "peninsula," you navigate around a "cape." If I am right, "capes" and "bays" go together and both represent features _of the coastline._ Thus, for example, Cape Cod separates Buzzard's Bay and Cape Code Bay. Of course, when a feature gets named, the name sticks. Most of these features were first seen and name by navigators. So many things are named "cape" (Cape Cod, Cape Hatteras, Cape Horn) and very, very few have "peninsula" as part of their place name. Again, this is just my theory.