Although angel food cakes and sponge cakes are similar in texture and even in flavor, when it comes down to the ingredients that go into the two cakes, there are a variety of differences. Although both cakes are light and airy, the similar properties come from two very different processes.
Although both cakes use a full dozen eggs to achieve the lightness and height, a sponge cake uses six egg yolks in addition to six whole eggs in the traditional recipe. In an angel food cake, egg whites are whipped and then folded into a batter, where in a sponge cake, the eggs are part of the batter itself and do not require egg whites to be whipped and folded.
The leavening process in the two cakes is the main difference between an angel food cake and sponge cake. An angel food cake will get its height and lightness from the addition of the whipped egg whites. Many cakes that have a light or airy feeling usually use egg whites as a leavening agent. Sponge cakes use the combination of salt, eggs and cream of tartar, a fine powder that also helps cakes and biscuits rise.
Many different types of flours are used for baking cakes, and although there is a special "cake flour" it is not the most commonly used flour. Angel food cakes use cake flour because the texture is so fine and needs to be sifted very finely. Sponge cakes, however use AP flour, which is the most typical flour in most kitchen pantries. This flour mixes better with the amount of butter that goes into a sponge cake.
Bake Temperature and Time
Baking an angel food cake is a longer process than baking a sponge cake. When baking an angel food cake, preheat the oven to 375 F and bake the angel food cake for 30-40 minutes or until the cake springs up when it is touched with a finger. When baking a sponge cake, preheat the oven to 350 F and bake for 25-30 minutes until the cake is brown and shrinking away from the sides of the pans.