Spot on Clint. A whole carcass would be cooked in a pit by the Pitmaster (one of the enslaved African Americans would be spared field duties and left to look after the cooking). The term BBQ has since expanded to also cover direct cooking of smaller cuts from bigger beasts.
Gas BBQ grilling is no different from charcoal grilling, but it’s a world away from an indoor cooker with an overhead grill. With both gas and charcoal, the bar temperature is much hotter so more Maillard reaction occurs on the surface of the meat and fat dripping onto the heat source underneath combusts to add a smoke character to the cook. The only addition that charcoal can add is the additional flavours the burning fuel can add. So, cheap B&Q briquettes make your burgers taste like petrol while single variety lump woods add their own aromas and flavour notes to complement the cook. If your doing low ‘n slow then that effect is amplified.
Charcoal is a bit like yeast; gas BBQ’ing or a basic hardwood blend lumpwood is like brewing with a neutral ale yeast and you get to appreciate your ingredients to their full. Aromatic single variety lumpwoods offer a similar diversity in end flavours and should be treated like any other ingredient.