When we went to Pompeii and Sorrento, the pizza had more sauce and was generally more "wet" than the other pizzas I have had. They also used a lot of olive oil, especially compared to the pizza from Northern Italy. This style of pizza also used a lot of Ocimum basilicum, otherwise known as basil.
When we went to Venice, the pizza was generally more light and didn't seem as heavy. There was still the wonderful Italian tomato sauce and mozzarella cheese, but it seemed slightly drier than pizza from the south.
This weekend, both pizzas from Bar Franca and the beautiful town of Vernazza seemed to encompass the best of both styles of pizza. It was still light and didn't have quite as much tomato sauce and olive oil as the Napoli pizza, and the dough was more dense than Venetian pizza. You could also really taste the flavor from the ovens they were baked in.
Despite the differences in pizza in various regions throughout Italy, one thing is certain. Pizza in Italy, no matter where it's from, is better than pizza from the United States. I will definitely miss Italian pizza when I am back home, and I will never look at pizza the same way again.