Boy, we spend a lot of time on DC arguing over minutia.
Bake and Roast are two words that mean essentially the same thing these days, but that have different origins. "Roast" comes from the old French "rostir". Bake comes from the Germanic "bahhan".
There are a lot of words in our language that are like this. For example, "Dine" comes from the French. "Eat" comes from the Germans. They both mean the same thing. In general, the French word is used to denote a fancier way of doing things.
One school of thought (and the one that makes the most sense to me) says that "roast", in the middle ages, was the term used to describe cooking food on a spit over an open flame. You would normally do this with the entire animal. Thus, Andy's interpretation is correct. "Bake", on the other hand, meant cooking in an enclosed (or partially enclosed) area, such as a brick or clay oven. It also was used to describe food cooked in a pot with a cover (think Dutch oven).
Since most of us don't have spits and open flames in our homes these days, we now tend to do most of our roasting in the oven. Old terms linger on, despite changes in technology. Maybe we should just refer to everything as "oven cooked".