Theravada schools have always stressed the ideal of reaching nirvana through detachment and desirelessness achieved through meditation. The heart of Theravada is its community of monks. Theravada Buddhist schools were developed in the earlier centuries of Buddhism to adhere to the original unchanged thinking of the Buddha; the way of the elders. Although Theravada does accept that laypeople can attain nirvana, the life of the monk offers a surer path. The notion is enshrined in the ideal of the arhat; a person who has reached nirvana. Mahayana (the big vehicle)-
Between the 1st century B. C. to the 1st century A. D. the two terms Mahayana and Hinayana appeared in the Saddharma Pundarika Sutra or the Sutra of the Lotus of the Good Law. Mahayana Buddhism spread out of India to central Asia and to China, which it entered in the first century of the Common Era. The Mahayana vision accommodates a large variety of people and suggests that Nirvana is not only attainable by monks but can be reached by everyone. In Mahayana, the Buddha nature can express itself in three ways, this is called the trikaya doctrine; law body, form body, or body of reality.
Vajrayana (the diamond vehicle)- Vajrayana is considered by some to be simply a special form of Mahayana. Most consider Vajrayana to be a third branch of Buddhism, because of its complexity and unique elements. It is a Tibetan Buddhism, a complex system of belief, art, and ritual. Vajrayana actually includes other forms of esoteric Buddhism. The monks within this branch of Buddhism were not only used as teachers but also as doctors, they were thought to have special healing powers. A form of Tantric Buddhism first entered Tibet in the seventh century and was spread by Indian missionaries.