One school of Buddhism holds that the oldest written texts (the Pali canon) embody Buddhism as the Buddha taught it. This school, Theravada, has been most influential in Burma, Thailand, and Southeast Asia. In the West, it has been wonderfully taught as Vipassana meditation. The ideal of this approach is the liberation of the individual, and many of its practitioners are monks.
As I understand it, original Buddhism underwent a revival around 500 A.D., when the Mahayana school developed. Mahayana Buddhism is more social, colorful, and varied than Theravada (called Hinayana by the Mahayanists).
Mahayana Buddhism centers around the ideal of the Boddhisattva, the person who reaches an enlightened state that permits total liberation, but turns away from it to work in the world to help others. Boddhisattvas are rather like saints in Catholicism, except that they reincarnate. Imagine being able to visit the living incarnation of St. Francis or St. Paul!
A third school of Buddhism developed in Northern India and Tibet--Vajrayana, or Tantric Buddhism. Tantra is best known in the West for its paintings of deities in sexual intercourse, and early visitors thought this referred only to sexual practices. Now it is clear that these images are metaphors for the union and transcendence of duality, separation, opposites.
Several Vajrayana masters arrived in America after the Tibetan diaspora. Their practices appear to build on the Theravada meditation, but extend to include other practices, such as