Okay, I was genuinely curious, because they seem identical. I did notice, like you said, that he is quite muscular and he does have good ball control. But a better dribbler? Hes fast but from the highlights (I know, I know) he doesn't look like hes got great ball control.
He's an excellent dribbler. If you watched more than a few highlights you would see this. This is what he's known for, his pace, his acceleration, his dribbling, his shot. He's got a decent crossing ability as well. His weakness is more so in decision making, although this is the case with almost every 20 yr old, and as they grow more experienced that improves, plus it isn't as bad as some members are making it out to be.
Iturbe is built like Messi. Similar height, very muscular, low centre of gravity, powerful on his feet. So he is taller, and vastly stronger than Giovinco, and does not get muscled over in and around the box.
Plus, Giovinco, isn't an example of someone we all could predict would flop. He was very good the two seasons prior to coming here. No one could have predicted with any certainty that he would fail here, especially if we had continued with a 4-3-3 with him playing wide. Asking a player of his physicality to play in the centre in a two man system and to challenge big defenders physically is one of the main reasons why he has been so mediocre. If we are actually attempting to use formations with attacking wingers, I would imagine that he could do very well for is playing opposite Iturbe and with Llorente/Tevez in the centre.