I read the difference between Theravada and Mahayana and found out Theravada got 18sects. I am wondering what are the differences between each sects and why it existed? But not just one whole Theravada?
Why is it in some mahayana books they wrote mahayana is Great vehicle but theravada is small vehicle. And I think I watched a show called journey to the west, from china that show was produced. The monk Táng-sānzàng was told by the guan yin boddhisatva that to able to preach the world and to help them liberate from samsara, he need to acquire the Great vehicle teachings but not small vehicle teachings.

