When I am asked what the difference between fiddle and violin is, I tell people that in my experience, playing the violin is like reading poetry in a second language and trying to give it all of the inflection that the original author would if he or she were reading it aloud. On the other hand, playing the fiddle is like dancing.
Both of these are rewarding and fun, but they are very different. And both are wonderful in their own right.
But if you want more direct and specific answers, this article is worth checking out.