Auto focus in nikon D90?

I have a problem with nikon auto focus option! I want to know the difference between AE lock and AF lock? Can you please help me?

AE is auto exposure lock and AF is auto focus lock. I use this button when shooting sports.

I make sure that my focus button is set to continuous and then when shooting, keep my thumb on the AF-L after focusing on my player. The lens will stay in focus as the player moves on the court

AE-exposure lock(lock the current setting)
AF-focus lock(lock the focus)

i use AE lock when shooting sport.

AE lock keeps exposure settings as you reframe the shot.AF keeps focusing as you move the subject away from center (in single focusing point mode at center). Ideally, you use both at the same time if you change framing.