AI Focus and AI Servo seem like the same thing to me.
AI Focus is suppose to continuously change focus if your subject is moving, but AI Servo only changes focus if "you anticipate the subject moving."
Either the subject is moving or it isn't. So why would I use one focus setting instead of the other?
To make things more confusing, the 5D Mark ii has a custom function "C.Fn III-7 AF Point area expansion" that is suppose to expand the focusing area when you are on the AI Servo focus mode. Isn't that the same thing as selecting all focus nodes with that button on the front top right of the camera with the square puzzle icon? Why use C.Fn II-7. I'm sure I'm missing something.