Several years ago I had a baking disaster in my mom's kitchen in Georgia, following a recipe (for biscuits, if you must know) that worked perfectly in California. I had a nasty puddle of wet flour instead of biscuit dough and threw the mess out. There I was, using ordinary all purpose flour in each case, but I got different results. My conclusion was that somehow all purpose flour sold in Georgia is formulated differently than all purpose flour sold in California. Was my guess correct? I don't know (yet).
So I have just started a project to record what the flour sellers reveal about their products and see if I can find a pattern that tells me what is going on with the different flours, at least the white ones. I rarely use whole wheat and I am not really interested in it.
I know that the wheat germ is removed when white flour is made. Some flours are bleached, some are enriched, etc. What does enriched actually entail? What difference does bleaching really make other than color?
When I'm done, at a minimum I expect to know which flour can be safely substituted for another. I'll keep you posted.