What is the difference between these two sentences?

Question

Wie geht es Ihnen?

Wie geht es dir?

Answer 1

They "mean" the same thing, (How are you?) but you say the first to someone you're on "Sie" terms with, the second to someone you're on "du" terms with.
Generally, you're on "du" terms with all children, with anyone in your family, and with people you've agreed to be on "du" terms with. I haven't really figured out how that part goes, though...