I love eating pizza, a traditional Italian dish consisting of dough and tomato sauce.  Do you enjoy pizza?
yes I eat it all the time
So it turns out the pizza we eat today is called "modern" pizza, which was first invented in Naples and now has become a staple dish throughout the world.
as opposed to what other pizza
You could say it's the "traditional" pizza, which was primarily made out of flat bread, also known as "panis focacius",.  The shape of it would be in a shape of a bread and not your round pizzas you see today.
so when did modern pizza start
The modern pizza was invented in the late 18th century, when tomato sauce was added to the pizza.