I have seen, on this site, several answers which make the violin and the fiddle identical instruments. In fact, my teacher, Boris Schwarz, used to call his instrument a fiddle
… (though he played classical violin). There is a difference, however, between the two. On the violin, the bridge has a typical curve that raises the strings and separates them from one another. Bariolage (moving from string to string and back again rapidly) is possisble because of the nature of this bridge. However, on a fiddle the artist might NOT want this traditional curve to the bridge and ask the maker to REDUCE the curve of the bridge to make bowing and double stopes easier. ( Full Answer )