The significant difference between cake and all-purpose flour is the amount of protein content. The amount of protein it has affects the gluten, which is created when kneading the flour. Gluten is the ingredient that determines whether breads are tough like rolls, or crumbly like a muffin.
Climate is also a factor in the amount of protein found in wheat. In the United States, all-purpose flour from wheat that is grown in Southern states has a protein content of 7.5-9.5 percent, while all-purpose flour from northern states has a protein content of 11-12 percent.
Cake flour, on the other hand, is finely ground. To achieve the perfect birthday cake or cupcake, do not use anything but cake flour. Typically cake flour contains 7-8 percent protein. Cake flour is created from soft wheat and is finely ground and chlorinated to render it more acidic and absorb water effortlessly so that the cake will rise, and it sets well.