Surface 1/2 are Wacom styli, Surface 3/4 are NTrig styli. I know this all too well because I got a Surface 4 and it was really great except for the part where

Surface 1/2 are Wacom styli, Surface 3/4 are NTrig styli. I know this all too well because I got a Surface 4 and it was really great except for the part where my main use for it was "run Adobe Illustrator in smaller spaces than a laptop and a drawing tablet require" and Illustrator drops the first half second or so of every line I draw with the pencil tool. I now have a Wacom Mobile Studio which is pretty good when it's not failing to connect to the pen/touch drivers after waking from sleep, which happens just often enough to be annoying. It's got enough other problems that I would replace it with an OSX-capable IPad in a heartbeat.