Darol: The difference between a fiddle and a violin, as famed jazz fiddler Johnny Frigo once told me, is "about $500 a week". Also nobody cares if you spill beer on a fiddle... If you're playing dance music or improvising any kind of popular music on a violin-shaped object, you're playing the fiddle. You can fiddle on anything; I've played good old Texas fiddle tunes on $400,000 Sradivariuses, and a 6 million dollar Guarneri (the Guarneri won).

That said, some VSOs (violin-shaped objects) sound better for fiddling than others. Generally, violins set up for classical music are optimized for maximum projection and brilliance, because most Western European Ethnic Music eschews amplification of any kind. Most working fiddlers play into a microphone or use a pickup to amplify the instrument, so most fiddlers prefer a mellow, smooth sound that doesn't sound screechy through speakers. Sometimes fiddlers will reduce the curve on the top of the bridge to make string crossing easier, since they aren't bearing down so hard with the bow, as a romantic-style classical player would.