Here is some more information I received from the Deals to Meals Monthly Newsletter a little while back that I found very helpful.
All-Purpose Flour -
is the finely ground endosperm of the wheat kernel separated from the bran and germ during the milling process. All-purpose flour is made from hard wheats or a combination of soft and hard wheat from which the home baker can bake a complete range of satisfactory baked products such as yeast breads, cakes, cookies, pasteries and noodles.
Enriched All-Purpose Flour -
has iron and B-vitamins added in amounts equal to or exceeding that of whole wheat flour. Bleached Enriched All-Purpose Flour is treated with chlorine to mature the flour, condition the gluten and improve the baking quality. The chlorine evaporates and does not destroy the nutrients but does reduce the risk of spoilage or contamination.
Unbleached Enriched All-Purpose Flour -
is bleached by oxygen in the air during an aging process and is off-white in color. Nutritionally, bleached and unbleached flour are the same.
Bread Flour, from the endosperm of the wheat kernel, is milled primarily for commercial bakers but is also available at retail outlets. Although similar to all-purpose flour, it has a greater gluten strength and generally is used for yeast breads.
Self rising flour is an all-purpose flour with salt and leavening added. One cup of self-rising flour contains 1 1/2 tsp baking powder and 1/2 tsp salt. Self rising flour can be substituted for all-purpose flour in a recipe by reducing salt and baking powder according to those proportions.
Whole Wheat Flour
Whole wheat flour is a course-textured flour ground from the entire wheat kernel and thus contains the bran, germ and endosperm. The presence of bran reduces the gluten development. Baked products made from whole wheat flour tend to be heavier and denser than those made from white flour.