Yeast vs baking powder/baking soda?

Think of dinner rolls, the texture, the way they taste. Now think of biscuits, their texture and taste. THAT is the difference. You can substitute yeast for baking powder in a quick bread (with a little more fuss), but you can't successfully substitute baking powder (and/or soda) in a yeast bread. You can make Irish Soda bread, which is rather like a scone you can slice. You can make cornbread, beer bread, biscuits, tortillas, flat bread. But plain old white or wheat bread, yeast breads, need yeast.