AP (All Purpose) flour is a blend
of hard and soft wheats ... the blend depends on where you live (in the North it tends to contain more hard than soft - in the South it is the other way around).
Bread flour is a high gluten flour ... think of the gluten content as the difference between chewing gum and bubble gum ... the bubble gum will hold more gas bubbles than the chewing gum (very simplistic example).
Have you checked our previous discussions on this subject?
If you want to start from scratch ... you might want to explore here
. There is a fantastic page on flour ... but I'll let you explore the site and find it.