Why we have Pressey? Who was argubly a superior college player to Smith.
Smith is a little more NBA proven.
So far, Nolan Smith has the NBA track record of a horrible player. Consider that he is one of the roughly 7% of first round picks who don't get their third-year option picked up.
It's a small sample size, but he had the lowest WS/48 of any player with 250+ minutes last season. While the stat isn't perfect, it's kind of hard to play 40+ games in two consecutive seasons with a below-zero WS/48.
So, Smith is a little more NBA proven in that he has so far been proven to suck.