During the Great Depression of the 1930s, Godfrey Irwin published American Tramp and Underworld Slang, within which he explained the difference.
Bums loaf and sit; tramps loaf and walk; but a hobo moves and works.
The word “hobo” is derived from “hoeboy”.
The term originated because many of the young men traveling the rails were from farms and carried a hoe with them so that they could work the gardens of those households that might employ them.
