There are 2 ways to get height, distance between clamp and the bend to the handles, and the angle from the bend to the actual handles. The first will be more similar to an increase in stem height, while the latter is akin to big sweeping bars on a street chopper. For most applications and most people (me included) a flatter bar is preferred, meaning that the bars sweep back from the mount less than stock and that they sweep up from the mount less than stock. This is a more aggressive riding stance and also results in a more direct feel when turning the bars. This is an advantage when racing becuase it allows for faster, tighter turns.
I'm not sure that any of that is clear, so I apologize in advance. Hopefully someone else with come along with a clearer description, or you can contact one of the handlebar companies that has more interest in helping you than telling you what they tell everyone else.