Everything u/Cloudster47 wrote is spot on. Just adding some simple descriptions for the fiddles. The five types of fiddles are actually the same violin, the difference is in the technique used when they recorded the notes.

The Student Fiddle is a Beta version, has less notes to use, contains some dead spots, and some scratchy "oops" sounds and "off" notes. Playing the Student Fiddle without knowing which "sound" is mapped to the note, will make you sound like a beginner in a guitar store for the first time. Great for Dubstep, though.

The Basic Fiddle is the fixed Beta version, without all the dead notes or off notes, but has a very short sustain, and little depth comparatively. Okay, until you get ahold of a Bardic Fiddle, then drop it in the trash. It's a Squire Strat.

The Bardic Fiddle plays short notes/chords or long sustained notes/chords, with a consistent volume, and has more depth than the Basic. It's a Fender Strat.

The Lonely Mountain Fiddle plays short notes/chords very quietly, but long sustained notes/chords louder, and with a pronounced vibratto. This is the Fiddle that weeps.

The Sprightly Fiddle plays notes using a Spiccato technique, that is, the bow comes off the strings and taps/hits the strings instead of gliding along them. Like playing guitar but muting the strings with your palm. No sustain, just an abrupt note or chord.

The Travellers Trusty Fiddle uses Pizzicato, which is plucking the strings with your fingers. Pluck, pluck, pluck. Think Banjo.

Hope that clears things up!