From the Mahayana perspective, those who follow Theravada or Hinayana practice are only concerned with their own eventual enlightenment, achieved after countless lifetimes of gradually improving one’s karma.
Because of this primary concern for one’s own enlightenment, this branch of Buddhism is sometimes called the Lesser Vehicle (not concerned with the larger welfare of the world, but for oneself).
However, this branch of Buddhism more often calls itself Theravada because it believes that it is following the original teachings of the Buddha as preserved by the early followers of the religion.
Thus, Theravada Buddhists state that they follow a senior or simpler branch of Buddhism, supposedly untainted by innovations that later came into Buddhism as it developed in the Mahayana direction