What's the difference between a violin and a fiddle? A violin has strings and a fiddle has strangs!
Fiddling is just the style of playing a violin in bluegrass music. It is known mainly as melody instrument, but no instrument can play melody all of the time.
Left - Ernst Heinrich Roth Violin - Any traditional violin can be used for bluegrass music. The main thing to look for is the use of solid woods in construction. Violins should have a solid spruce top and a solid maple back and sides. The fingerboard should be genuine ebony and the pegs should be hardwood - like ebony, rosewood, or boxwood.
Right - Glasser Carbon Composite Violin - Some bluegrass fiddlers are finding more options in modern violins. They can be found in 5-string models and made from durable materials like carbon fiber. Additional items like geared tuning pegs and pickups can make for very versatile instruments. A 5-string violin adds a low C string - like a viola. This low string sounds especially good when used for rhythmic accompaniment.