Italy and Juventus have mainly the same players. Buffon, Barzagli, Bonucci, Chiellini, Marchisio, and Pirlo are all regulars in both. Now we individually compare the rest.

Maggio vs Lichsteiner
Balzaretti vs Asamoah
De Rossi vs Vidal
Cassano vs Vucinic
Balotelli vs Quagliarella
Di Natale vs Giovinco

I don't think that these players match up exactly, but if I had to choose...

Maggio vs Lichsteiner
Balzaretti vs Asamoah Unfair match though - I don't think Asamoah has ever played as a WB.
De Rossi vs Vidal ... too difficult to decide. Vidal is no longer a DM so this match-up is too much of a stretch. I like both players.
Cassano vs Vucinic
Balotelli vs Quagliarella
Di Natale vs Giovinco

Asamoah's the appropriate comparison Forza, he's been great as wingback for Juventus, though it's important to note that against Shakhtar he showed his defensive naiveté, however he should be compared with Criscito, who I would prefer given the need in my eyes for a true defender.

This shouldn't be about individual comparisons however. Each Italian or Juventus player might be superior, however it's irrelevant to how formidable a team they comprise. It's also then worth asking whether we want to consider a hypothetical Italian side which gets the opportunity to train together each week as Juventus do, essentially asking whether Juventus would be improved if they quite literally were the national side, or if this refers to what each individual might add in the few games a year that the national side actually plays.

Maggio vs Lichsteiner
Balzaretti vs Asamoah
De Rossi vs Vidal
Cassano vs Vucinic
Balotelli vs Quagliarella
Di Natale vs Giovinco

Italy more depth and players play with more passion internationally usually. Italy is definitely better although this is usually the case with a club vs. international team.