"in" refers to borders, "on" refers to being on the surface of a particular location. SuKi gave some good examples: in China but on a mountain

Generally when you use "located in" it is referring to a specific location within a larger setting. So, if you were in a library and you wanted to know which section you would find a certain book, you would ask, "what section is this book located in?". "Germany is located in Europe." "Located on" is usually used for directions or far away locations. "That house is located on main street."

Located on means on top of something. Located in means inside something.

Located in a building. in a town. in a country Located on a mountain. on an island.

Thank you so much for the explanations! They are all easy to understand!