?_Lehmann:

How can the characteristics of pizza define its style?

When the characteristics of certain pizzas are are similar to the characteristic of those pizzas made predominantly in certain cities, or geographic regions, those pizzas are said to be of that style. For example;
In New York City, pizzas typically have a nearly burned bottom crust characteristic, are hand formed (tossed), have a thin, somewhat bubbly crust, and has the cheese applied in pieces rather than as a uniform layer over the pizza, and a rather tough, chewy eating characteristic. When a pizza posses all or most of these characteristics, the pizza is said to be of New York style.
There are probably hundreds of different styles of pizza. Some are even identified by the maker, such as a Pizza Hut style of deep dish pizza.
I hope this answers your question.
Tom Lehmann/The Dough Doctor