Baking soda and bicarbonate of soda are different names to identify the same product. They are both leavening agents. However, the reaction that they give when mixed with other ingredients offers a unique outcome.
Baking powder is a mixture of baking soda, a filler, and a dry acid. When a liquid is added to it, it creates a reaction, which causes bubbles to form in your batter. This causes the batter to expand, creating a fluffy baked good!