What's the difference between a violin and a fiddle, the main difference is in the styles of music played between the two instruments.
Any string instrument played with a bow can be referred to as a fiddle this includes violins and violas, a violin will mainly be used to play classical pieces while a fiddle will be used to play ethnic or folk music.
Also musicians with formal training will tend to play classical music on violin while untrained players will play folk music on fiddle.
The construction of a fiddle and violin are identical except that some fiddles are fitted with a flatter bridge than classical violin.
Although this difference is smaller than about a quarter or half a millimeter the height variation it creates in the strings allows players to play double easier.
It also makes triple stops possible allowing fiddlers to play chords.
The strings used also define the difference between a violin and fiddle.
A fiddle will use steel strings rather than gut horse hair or synthetics as the sound of steel strings more suites the music played by fiddles.
You will also see fiddles fitted with fine tuners as steel strings are much easier to tune with fine tuners, it is very uncommon to see fine tuners on a full sized classical violin.
Fiddlers will almost always play on their own or with a group of other instruments while violin are grouped in sections.
The standard bow is used with both violin and fiddles.
Remember while violins and fiddles are identical in construction and usage, what defines a violin or fiddle is the type of music played on it.
A violin is used for classical pieces and a fiddle is used for ethnic and folk music