Have you ever wondered what the difference was between a standard guitar and a baritone guitar? Premier Guitar has a pretty good write up about baritone guitars, written by Sweetwater Sales Engineer Art Hill.
In essence, it comes down to scale length. The scale length of a baritone guitar rests between a bass guitar and a standard guitar. As a result, baritone guitars often use heavier gauge strings and are tuned down lower than standard tuned guitars.
I was surprised to found out the diversity of artists that have used baritone guitars. Duane Eddy, George Harrison, John Lennon, Joe Perry, Johnny Cash, Dave Matthews, and Stevie Ray Vaughan all used baritone guitars at some point in their career, among many others.