Teddy spreads the ball, and goes through his progession more at this point in their careers. There's a reason Robby Anderson has disappeared from the offense.
Sam usually locks in on his first read and is more turnover prone.
He does have a better arm than Teddy and can make some pin point throws, especially on the run and with this Oline that's a benefit.
All in all I think Sam has greater potential and if he can cut the turnovers down. The sky's the limit on where this team can go.