When the flour is processed by removing the germ and bran of the wheat grain, the bread becomes white bread because only the white, starchy endosperm is left behind. The white bread thus formed contains added sugars.
Whereas in the brown bread, nothing is removed and the whole wheat flour has the germ and bran. Due to presence of the germ and bran, this bread so called brown bread contains more nutrients, - fibres, proteins, vitamin E, and vitamin B, magnesium, iron, phosphorus, potassium and zinc. That's why the fitness experts advise to eat brown bread instead of white bread.