Bicarbonate of soda is also known as sodium bicarbonate. It is a strong leavening agent which is about 3 or 4 times stronger than Baking Powder.

A chemical reaction happens when the soda meets an acidic liquid (for example lemon juice or vineagar) and it adds air into the mixture.

Meanwhile, Baking Powder contains baking soda along with Cream of tartar and cornstarch.