What's the difference between a sunroof and a moonroof?

According to dictionary.com a sunroof opens and a moonroof is just a fixed window. However, I am not convinced this is true across the board; the Mazda had a "Moonroof Windscreen" (or something like that) as an option, and I tend to think that implies the option of opening the, er, skylight. (Also, on further inspection, the Moonroof is listed as Power sliding-glass moonroofwith "one-touch" open feature. If that doesn't mean it opens, I am a horse's ass. And also illiterate.) So there is, in fact, no difference. Just like boys and girls, or pirates and ninjas.