There are many different types of cake recipes and many different ways of dividing them into various categories, but they are generally classified according to whether or not they contain fat, also known as shortening (not the be confused soley with just processed shortening). Thus, cakes are either: SHORTENED (BUTTER OR OIL) CAKES or UNSHORTENED (FOAM) CAKES. Chiffon cakes make up the third category, but here they're included with unshortened(foam) cakes.