They have different uses.
Baking powder is a key leavening agent in everything from pancakes to cakes, helping baked goods, breakfast treats, and more ...
Baking soda and baking powder are both used in baking, but they are not interchangeable.
Choosing between baking soda and baking powder is one of those small decisions that quietly determines whether a recipe turns out light, tender, and evenly risen, or flat, dense, and oddly bitter.
Flat, dense cookies? Not a chance.