I am often asked if doing college level games is difficult........and to a point they are...the speed of the higher game is the factor that requires the most adjustment....but the level of play and player makes much of the game "easier" to call.........
For the most part you do not see the wide ranges of abilities, errors, inconsitent play that is seen in HS....and most certainly at the youth level......
The difficulty and responsibility in calling the higher level game is adjusting to the speed and the need to be highly accurate from a rules and mechanics front.