(BTW, go to www.onelook.com and bookmark it. There’s your answer to almost any word meaning question.)
RE: Duvet
I believe what makes a Duvet a separate thing from merely a French word for comforter or blanket is two characteristics: 1) A washable cover (very difficult to wash down comforters – better to simply wash the cover); and, 2) since the duvet has a duvet cover, then one doesn’t necessarily need a ‘top sheep’ on a bed (but I do anyway, since the top sheet cloth has a much nicer feel than the duvet cover).
I’d heard the word “duvet” before, but didn’t know what it meant until my GF recently educated me on the topic. In my mind a comforter, or duvet, is not at all the same as a blanket; a blanket is basically a sheet of some kind of thick textile, suitable for sitting on at a Fourth of July picnic, while a comforter or duvet is actually stuffed with something, be it cotton batting or eiderdown or whatever. A comforter is a lot warmer than a blanket, since it traps a layer of air inside it in addition to the air that is trapped under it.
Anyway, on to The Duvets of Bienville:
It seems as though all the versions of “Over the Rainbow” that I’ve heard in the last few years owe a lot more to Israel Kamakawiwo’ole’s version than to the Judy Garland version in The Wizard of Oz. Not sure how likely that is though, Iz not having received much airplay outside of Hawaii (as far as I know).