To avoid baking catastrophes, it’s vital for any baker worth his/her measuring spoons to know the difference between baking powder and baking soda. Sure they are both chemical leaveners and produce a bit of top texture in recipes that don’t use yeast. The difference (other than one has a muscular arm holding a hammer on the box and sits in a back of your grandma’s fridge for like 35 years) is that they do the fluffing in different ways.
Baking soda, or sodium bicarbonate, is used in recipes with acidic ingredients (i.e., vinegar, lemon juice, buttermilk, molasses, or yogurt), as when the two mix, carbon dioxide bubbles form, creating the leavening, which causes baked goods to spread.
Baking powder is a combo of baking soda (an alkali) and a powdered acid (such as cream of tartar), and when moistened in a dough/batter, a chemical reaction happens that produces carbon dioxide gas that inflates or puffs baked goods.
If all this is too much, just remember: Soda spreads and powder puffs.