Several have mentioned the fiddler playing double stops, but many are also playing triple stops, and maybe even all four strings. No one has yet mentioned the critical difference in the fiddle and the violin - If the instrument is carried in a case it is a violin. If it is carried in a flour sack, it is a fiddle. Have enjoyed and been enlightened by this discussion. I work in music park where this question pops up frequently. It will be nice to have something to add after the case and flour sack.