The "defining line" if there is one, is probably the barrel thickness. Fowlers traditionally have a thin walled barrel used only with shot, while more versatile smooth rifles have thick walled barrels that handle shot, but also a ball if need be.
Southern guns don't always fit the mold of eastern pieces. We may be looking at a regional differentiation here. Southern areas often seemed to get "more value" or more flexibility out of their products, perhaps due in part to a somewhat lower standard of living for many of its citizens compared to the average northern citizen. Thus the smooth rifle that did two functions, shot for small game and ball for larger game, was more efficient (and lower cost) than having two different, and individually more restricted, firearms. Perhaps a wealthy southern planter or merchant could afford both types of arms, but the average man would more likely turn to the smooth rifle, the best of both worlds for him, for local use.
The variations in details, such as octagon-to-round barrel vs. octagon barrel, cheek vs. no cheek, etc., may be simply internal regional preferences in the south. The key seems to be longer barrels than comparable rifles of the day, and a smooth bore often somewhat larger than bores in its rifled counterparts. I would also think that larger game lasted longer in the south than the eastern states, so the smooth rifle or smooth bore continued to have value, while back east most big game was gone, and the fowler with shot could handle most of the small stuff that was left. Shelby Gallien
