A good question and perhaps it's a bit like art... I know it when I see it.
But I can give you several examples of control that definitely isn't submission. I give up control to airline pilots and bus drivers. I give up control to dentists and doctors (for the length of the visit at least.) I give up control to my masseuse... and I've even given some machines total control over me, elevators come to mind.
But none of that qualifies as submission...