I can't tell the AF difference

mainly because I don't feel there is any difference nor do I know how to measure the difference.

I like the D300 + 80-200mm better because I could easily use F4 and ISO 400 to get the shutter speed up there to get much more clear photo.

One thing I did notice was that 11 point focus is much fast than the 21 point focus when I am shooting CH mode of the horse which is moving vert fast .