Whole wheat flour is much more nutritious than white flour (Maida) as maida is a refined product of wheat - meaning it is obtained after processing the wheat, which makes it less nutritious. The lesser a grain or vegetable is processed the more nutrients it retains. The outer brownish layer is removed from the wheat and the inner white portion is used to make maida flour. Whole wheat flour contains fiber and various other nutrients which are missing in maida.