The 
FidDle is the same MusicalInstrument
? as the VioLin
?.  Essentially, "fiddle" is used to described a violin when the violin is played in a FolkMusic
? (i.e., TraditionalMusic
?) or sometimes a JaZz
? style.  One very slight difference between fiddle and violin occurs in American (e.g., BlueGrass
? and OldTime
? music) fiddling: the ViolinBridge
? is shaved down so that it is essentially flat.  This makes it easier to play 
DoubleStops.