[This tip comes from a reader named Laura.]
Traditional all-purpose, or white, and whole wheat flours are milled from hard red wheat berries; both flours contain the wheat's endosperm, while whole wheat flour also contains the bran and germ.
Whole wheat white flour is milled from the hard white wheat berry. It contains the entire wheat berry; the difference is in the white berry's bran, and the result is a lighter colored, sweeter tasting flour. Retaining the bran and germ yields a flour with more fiber and naturally occurring nutrients.
It's often assumed that whole wheat white flour is made from soft white wheat berries; it's actually whole wheat pastry flour that is milled from the soft white berries. Ultimately, you can always check the label, but do know that King Arthur Flour and Bob's Red Mill (two of my favorite brands) both use the standards described above.
For the home baker, whole wheat white flour can be substituted in cookie, muffin, quick bread, and brownie recipes, for a start. It lends a milder flavor to yeast breads containing whole wheat.
P.J. Hamel, Editor of King Arthur Flour's Baker's Catalogue, gives this tip in a recent issue of The Round Table e-mail newsletter: "When making brownies with (white) whole wheat flour, I've found it s best to let them rest overnight before serving. This extra time gives the bran a chance to soften, negating any possibility someone will notice a 'branny' texture."