"It SEEMS like mandolin would be the result of an illicit union between a guitar and a fiddle..."
Isn't that how orcs were created, too? :) Okay, I'm looking up what my enecylopedia says on "mandolin" now, and it says, "It was probably copied from the lute", and also the 4-stringed mandolin is "tuned in fifths, like the violin". Now a fiddle is basically a type of violin, right?--wonder if that would fit with the guitar/fiddle union theory.
A fiddle IS a violin, yes.
Two different names for the same thing. In general, classical musicians call it a violin, other styles refer to it as a fiddle.