I think I've always used them interchangeably up to this point
Tramps and hobos are commonly lumped together, but in their own sight they are sharply differentiated. A hobo or bo is simply a migratory laborer; he may take some longish holidays, but soon or late he returns to work. A tramp never works if it can be avoided; he simply travels. Lower than either is the bum, who neither works nor travels, save when impelled to motion by the police.
~ H. L. Mencken
This counts as the one thing I've learned today