What's the difference between violin and viola bows?
Violin bows are sized proportionately with the violin sizes (3/4 violin uses a 3/4 bow), with the exception of 7/8 violins, which use a 4/4 size bow.
Viola bows are only available in "full" size. Full viola bows are the same length as a 4/4 violin bow. Violists seeking fractional- (child-) sized bows for violas 14" and under simply use a violin bow. For example, a 14" viola player would use a 4/4 violin bow, a 13" viola player would use a 3/4 size violin bow.
Viola bow sticks are heavier than violin bows in order to pull more sound out of the thicker strings and lower registers. Likewise, the frog is wider than a violin frog so the ribbon of hair can make more contact with the string.
Fun Fact: The way to determine the difference is that a viola bow's frog is rounded on the corner. A violin bow has a square corner on the frog.
