The wheat grain contains three parts: the bran, the germ, and the endosperm. Whole wheat flour is made by grinding the entire wheat grain. White flour is made from only the endosperm part of the wheat grain, which is pale in color and produces a softer flour.
Whole wheat flour is darker in color, more flavorful, and contains more nutrients than white flour. It does, however, have a coarser texture and is more absorbent than white flour, requiring a higher liquid ratio. The bran and germ present in whole wheat flour also work as little knives, cutting through gluten networks. Therefore, it is more difficult to build a strong gluten structure when working with whole wheat flour. This can lead to more dense and heavy baked goods.