Flour is grains, seeds or roots that have been grounded into powder. Flour is made by milling--or grinding grains between steel wheels or stones. When you purchase stone-ground flour, this means the flour was made with stone grinding. White flour is simply regular flour that has been bleached with a whitening agent. Made from durum wheat, semolina flour, has a coarse, rough consistency in comparison to white flour.
"White" actually refers to several types of flour: (1) plain flour that doesn’t have a leavening agent aka all-purpose flour, (2) self-rising flour with a chemical leavening agent (usually baking powder) and (3)enriched flour (flour that has added nutrients, those that were lost during the refining process are replaced in the final product).
The most common white flour, and the one you're probably most familiar with is made from wheat. Depending on which variety of wheat is used, the flour can high or low amounts of gluten.
Semolina flour differs from white flour in the way it's processed and the type of wheat that's used. Semolina is made with grooved steel rollers. The rollers crack the starch of wheat kernels into coarse pieces which is then ground into flour. The starch itself is the semolina. The semolina gives flour a yellow color and comes from a harder variety of wheat. It has high gluten content and a considerable amount of protein.
White Flour Uses
All-purpose white flour is the standard household flour because it is inexpensive and versatile. It can be used for a wide variety of baking and works especially well for cookies. Bread flour has high protein content, which is good for yeast bread breaking. Cake flour is, of course, used to make cakes. The flour has low protein, creating soft cakes. Pastry flour falls in between all-purpose and cake flour and is used in muffins, pies and pastries.
Semolina Flour Uses
Because of its sturdy nature and ability to hold shape in water semolina flour is commonly used to make pastas. It can also be combined with durum flour to make couscous. You can also use semolina to create a non-stick surface when baking.
Halvas is a popular Greek dessert made with semolina, sugar, butter, milk and pine nuts. In northwestern Europe and North America, semolina is sweetened and boiled with milk to make a pudding. In Scandinavian countries, semolina is served as a breakfast porridge.