Theravada - Mahayana - Vajrayana

Theravada:

The "Way of the Elders." It refers to the tradition of Buddhism that focuses on the classical ways of awakening. It is the common Buddhist tradition in Sri Lanka, Burma, Thailand. Cambodia, and Laos. It is very popular in North America, Europe, and Australia.

Mahayana:

The "Great Vehicle." This name refers to the tradition of Buddhism that accepts a wide and growing range of awakening. It is the common tradition of Buddhism found in China, Tibet, Mongolia, Korea, Vietnam, Taiwan, and Japan. It is very popular in North America and Europe.

Vajrayana:

The "Diamond" or "Thunderbolt" Way. Although Vajrayana is included under the Mahayana umbrella it is a very distinct form of Buddhist Practice. It focuses on the relationship with one's teacher and a variety of symbolic practices, including deity meditation and tantric practices.  It is the tradition of Buddhism found in Tibet, Mongolia, the Himalayas, and parts of China. It is very popular in Europe and North America.