It's not a mere dead stick "stylus" used just to touch a screen, but a sophisticated electronic device that controls the width and flow of the line being drawn on the screen. It is far more than a dead stylus. Its electronics interact with the electronics of the iPad Pro to do much more than a mere stylus ever could. You need to see the demos to even begin to grasp what it can do that a stylus could never begin to do.
My Wacom does the same thing with a pressure-sensitive tip!
Ed