This is a short answer to your question. But much more detail is available online. At one time there were 3 great traditions in Buddhism. These were Mahayana, Theravada, and Hinayana. Two traditions are still active today, Mahayana and Theravada. In the Mahayana tradition a follower seeks to attain enlightenment not only for themselves but for the benefit of all sentient beings. These people are referred to as Bodhisattvas. The Mahayana tradition is the largest of the two Buddhist traditions active today. It was started sometime about 400 years after the Buddha's death. One of the great Masters of Mahayana was Nargajuna who taught on emptiness. The Theravada tradition was started after the Third Council after The Buddha's death. This council was held to remove some heretical beliefs and wr