I think the bread confusion is coming from the fact that there are more than just the two categories. It's not sour vs sweet like, say, pickles. It's more like there's regular sandwich bread (French, Italian, pizza dough, etc); sweet bread, which is basically cake as Bondo said (banana-, cinnamon-, etc); and then sourdough, which is fermented with a specific type of airborne bacteria. (or something like this)
Adding to the confusion are Sweetbreads, which are disgusting head meats.