Fresh milled flour is flour that is milled, or ground right before it is baked. All of the nutrients are intact and fresh. That's it!
Now the long...er version
There are three components to a grain kernel. The endosperm, germ, and starch. The endosperm is the brown casing that encircles the entire grain. The germ is the seed like component in the middle, that is akin to a yoke of an egg. It contains the life of the grain, and will be what sprouts into a new plant. It contains the vast majority of the nutrients of the grain. The starchy white part of the grain is the white fluffy part that you might recognize as all-purpose flour. It is the starch and protein that serves as food for the germ until it is planted.
"The difference between flour bought at the store and fresh milled flour is night and day."
There is no comparison between the health of these seemingly similar flours. One is extremely healthy for you, the other is a primary reason for the obesity epidemic in the United States.
All purpose flour is simply the white starchy protein part that has been sifted out during the milling process. The two brown parts that contain all the nutrition of the grain are taken and given to other purposes that don't involve human consumption. This white flour is the base ingredient of most of the crackers, chips, tortillas, breads, and other grain based products in the middle shelves of grocery stores. This is simply a tragedy. People think because it says "enriched" that it somehow isn't bad for you. It is enriched because government mandates that some of the nutrients be infused back into the flour after it is completely stripped bare of all nutritional content through the sifting process and major health epidemics were occurring throughout the country in the early 1900's when commercial sifting began to destroy grain products as we knew them.
Look around in your traditional grocery stores at the carts of consumers. You'll be hard pressed to find two carts in a row void of this horrific "food." This is a tragedy that very little people are aware of the health risks of eating fake bread and ritz crackers. It doesn't help that most of these foods are marketed as FDA approved, and "heart healthy." Heart healthy my asshole. Crackers, chips, breads, pastas, cookies, cakes, cereals that are made from this stuff is why the average person nowadays looks like a flabby whale.
Tying it all together
Buy a grain mill, mill your own flour, bake your own bread, and have a healthy life! It is convenient to have these bulk bags of flour. They store indefinitely! There's a reason Joseph made silos and saved grain for 14 years to save the population during a 7 year world famine! This is the bread of life! Make this change and see the health benefits and the taste benefits immediately!