Theravada is the only surviving part of the Pali school, considered the oldest school of Buddhism. Theravada emphasizes individual enlightenment; is to become an arahant, which means "worthy one" in Pali. An arahant is a person who has realized enlightenment and freed himself from the cycle of birth and death.
Beneath the arahant ideal is an understanding of the doctrine of Sanskrit - the nature of the self. Very basically, Theravada considers Sanskrit to mean that an individual's or personality is a fetter and delusion. Once freed of this delusion, the individual may enjoy the bliss of Nirvana.
Mahayana, on the other hand, considers all physical forms to be void of intrinsic self and individual autonomy to be a delusion. Therefore, according to Mahayana, "individual enlightenment" is an oxymoron. The ideal in Mahayana is to enable all beings to be enlightened together.