Ha! Good one, Hugh! And certainly not where I was looking. (The prologue, appendices and the Party, to start with.)
The difference is generally probably about 3 feet, since the Appledores are men and the Mugworts are hobbits, though both are inhabitants of Bree.
The men of Bree seemed all to have rather botanical (and to the shirefolk rather odd) names, like Rushlight, Goatleaf, Heathertoes, Appledore, Thistlewool and Fernu (not to mention Butterbur). Some of the hobbits had similar names. The Mugworts, for instance, seemed numerous. But .......