Let me preface this by saying Curtis Jones is one of my favorite Clones of all-time.
Mason is taller, has more length, a far better handle, and more natural shake and ability to take his man off the dribble.
Now Curtis was a pure shooter and natural scorer. Time will tell if Williams has that same "it" factor.
If Williams gets stronger and gets more consistent with his jumper (as CuJo did) he has a ridiculously high ceiling. From a pure intangibles perspective this dude could play 2 guard in the NBA.