Talent concentration is bigger in Summer League, but college teams have an advantage of extended preparation: they can run sets, because they learnt to execute them, they have much stricter hierarchy, because no one is fighting for their future right here, right now and so no chucking or selfish play (well, there is, but not as much as in Summer League). So in short, Summer League is better indication of players one-on-one ability (on both ends), while college gives a better understanding, how a player functions within team structure. Obviously after 6-7 games you start seeing cohesiveness in team play in Summer League as well, but it is still more structured in college for sure.