Thanks, exactly what I was looking for :)
One could even argue that they mean the same thing, because the name for narcissus in Chinese is water fairy.
That was the other thing I was thinking, though I forgot to mention it. I believe that the name Narcissus is a western name (I'd bet that it's based on the myth, but I wouldn't know), so it stands to reason that they'd probably have their own name for it - especially if the flowers grow natively over there as well.
Also, I was talking with a few friends recently about the translation of "仙". It doesn't really translate that directly into English (see also http://teadrunk.org/viewtopic.php?pid=123#p123). "Sprite" and "Fairy" all have specific connotations in English that don't really convey how people describe the idea of 仙.
That's always the hard part about these things - when it comes to anything spiritual or mythical, there's hardly ever any kind of comparison. The two ways of thinking just seem to be completely different in most ways. Probably just about like trying to compare Native American ways of thinking.
On a completely unrelated note this reminds me of the fact that I have a big (13oz) yixing pot with a "water sprite" for a handle - though I really bought it for decoration, which I still have to figure out what I want to dedicate it to (since I really don't brew in that quantity). It seems logical to brew shui xian in it "big pot style" (that's what they call it, right?), but it would probably get used more for Chinese red teas, for the rare occasions that I drink it.