The two major schools of Buddhism, Theravada and the Mahayana, are to be understood as different expressions of the same teaching of the historical Buddha. Because, in fact, they agree upon and practice the core teachings of the Buddha’s Dharma. And while there was a schism after the first council on the death of the Buddha, it was largely over the monastic rules and academic points such as whether an enlightened person could lapse or not .....
Source: buddhanet.net