BREAD FLOUR is milled from either hard red spring or hard red winter wheat.
It is high in protein (typically 11.5 to 13.5% protein) that forms
good-quality gluten, essential for high volume and fine crumb in
yeast-raised baked goods. Bread flour can be purchsed bleached or
unbleached. Sometimes it contains added malted barley flour to provide for
better yeast fermentation, dough handling, and shelf life. Bread flour is
typically used for pan breads, rolls, croissants, and sweet yeast doughs.

ALL PURPOSE (AP) FLOUR is not always used by professional pastry chefs.
However, it is sold in the foodservice industry as H&R Flour, which stands
for Hotel and Restaurant Flour. AP typically has between 9.5 to 11.5%
protein, but this can vary with the brand. While AP flour is often made
from a blend of hard and soft wheat, this is not always the case. Some
brands, like King Arthur flour, are made entirely from hard wheat. Other
brands, like White Lily flour, are made entirely from soft wheat. AP flour
comes bleached or unbleached, and may contain added malted barley flour.

Not all professional bakeshops stock AP flour. What should be done if a
formula calls for AP and none is available? For yeast-raised products, use
bread flour instead. Additional water will be needed to develop the gluten.
The dough will handle more easily (won't tear or break as easy), the bread
flour will be higher than if it was mde from AP, and will have a finer crumb
(smaller air cells). The crust will brown more readily and the crumb will
likely be less white. The bread will not stale as fast and expect a slightly
different flavour.

Charles Baker (that is my real last name).