What is the difference between cocoa and carob powder?

Carrot cake and chocolate cake contain different ingredients. Chocolate cake is made with some form of chocolate, such as cocoa, and is usually topped with white or chocolate icing. Carrot cake is made with carrots, cinnamon, and is usually topped with cream cheese icing. Pecans can also be included in carrot cake, and can be put in the cream cheese icing, but this is optional.