This is how Buddhism changed. Buddhism changed because as Buddhism spread from country to country, people changed it a little.They then introduce other people to the religion. They learn how Buddhism was to them and when they introduce it to someone else,they decide to change it. So from the original it has been changed many times in many different countries. They would change it so it matches their home style.Then,they consider it as their own creation.So every time people worship Buddhism,it will remind you that it is different everywhere.Also, it tells you that sometimes people change or tweak things a little so it matches their kind of style or law. That's how Buddhism has changed.