There are many schools and practices in Buddhism. They can be roughly grouped into three types:
Theravanda or Southern Buddhism
Theravanda (Doctrine of the Elders) is the dominant school of Buddhism in most of Southeast Asia.
It's followed by 100 million in Sri Lanka, Thailand, Burma, Cambodia and Laos.
Its scriptures are preserved in Pali, an ancient India language closely related to Sanskrit. Theravanda (lesser vehicle) is the only surviving representative of the historical Nikaya branch.
The Pali Canon, is the collection of agamas or nikaya sutras.
The nikaya sutras are considered to be the oldest of the surviving types of Buddhist literature, and they are accepted as authentic in every branch of Buddhism.
Mahayana or Eastern Buddhism
The Mahayana (literally "Great Vehicle") branch emphasizes universal compassion and the selfless ideal of the bodhisattva.
They believed that the Law Sakyamuni taught in public was for ordinary people, in order to attain self-salvation.
It has co-existed with Confucianism, Taoism, Shinto and Communism.
It is followed in Korea, China, Japan and Vietnam. It is still a significant religion for a very large population (Between 500 - 1,000 million).
Tibetan or Northern Buddhism
Called also The Vajrayana, "Diamond Vehicle", Mantrayana, Tantrayana, and Tantric or esoteric Buddhism, shares many of the basic concepts of Mahayana.
The Tantric cultivation method includes male-female dual cultivation.
It is claimed that a practitioner can achieve enlightenment in one lifetime, or as little as three years, by using psycho-physical energy for concentration and awareness.
Its canons are preserved in Tibetan and it is followed by 10 - 20 million in Tibet, Mongolia and in parts of Nepal and Himalayan India.