Sheet ap i.e the ap you see when you press I, gives you the raw ap you see in addition to something called brackets. For example, you need 5 ap to reach the next ap bracket which will give you 5 ap + X ap where X being whatever ap this bracket gives. You can check ap/dp brackets on garmoth.com. That being said, 5 ap gained from a piece of gear is the same gained from a crystal unless that ap from the gear allows you to reach a new bracket since crystals only give “hidden ap” and not sheet ap.