If you’re new to orchestral music, the string family of instruments can be a little confusing. Besides size, what’s the difference between the viola and the violin? Or the cello and double bass? Size, not surprisingly, plays a huge role in setting the instruments apart. But there are other differences…
The figure below is actually a recreation of an image from DK’s Eyewitness book on Music, but I added one new variable, primary clef, with an explanation below.
The figure shows the range of notes for each instrument based on what is called “first position.” The benchmark is middle C, approximately the center of a piano keyboard.
First position means exactly what you might think: The lowest note on each string is an open note — basically, if you were to pluck each string without even touching the neck. The highest note would be your fourth finger placed on your highest string. (The highest note in first position will vary for each instrument). So based on the figure above, a violin with standard tuning can’t play any of the low notes that, for example, a viola with standard tuning can produce on its lowest string.
That’s what primary clef describes. There are various pitches music can be written in, and the symbol at the very left of a staff (the clef) tells you which pitch the music is meant to be played in. From lowest to highest, the clefs are bass, tenor, alto, and treble. The double bass and cello primarily use bass clef, the viola primarily uses alto clef, and violin primarily uses treble clef. (For comparison, guitar uses treble clef while a bass guitar uses bass clef. Piano uses bass and treble clef for the left and ride sides of the keyboard respectively.)
The size of the instrument is a good gauge on how low of a note the instrument can produce, but don’t be fooled. Once you move past first position, the string instruments can be incredibly versatile. Music for cello can be written in bass, tenor, alto and treble clef! Viola also can play treble clef, but it can be very difficult to hit those higher notes.
Gist for creating the figure above.
 The strings on a violin are tuned G-D-A-E, while the viola and cello are C-G-D-A. The cello, however, is tuned one octave lower than the viola (C3-G3-D4-A4 vs C2-G2-D3-A3). The double bass is similar to a bass guitar in that it is tuned in fourths, E-A-D-G, and it is an octave below the cello (E1-A1-D2-G2).