He is a better passer and has more experience. It can be argued that King's mobility gives them an added dimension, but his limitations, particularly his arm, hindered that offense. The players definitely pay attention during the pre-game ceremonies, and some get very emotional. Vinny Testaverde was affected by everything, growing up in New York, and his father helped build the World Trade Center, so it hit close to home for him. You saw Terrell Owens with a tear running down his cheek when the 49ers played the Rams two weeks ago.
Fans are different as well.
There's less booing and ragging on players. You get the feeling that people realize how petty those actions were. During the games, there's no difference, but certainly there's a different tone since everything happened. You can see the patriotic mood in the stadiums. The crazy thing is, like his first injury, he hurt it without contact with another player.