- Astika systems: Accept the authority of the Vedas (e.g., Samkhya, Yoga, Nyaya, Vaisheshika, Mimamsa, Vedanta). - Nastika systems: Reject the authority of the Vedas (e.g., Charvaka, Jainism, Buddhism). - The distinction is not primarily based on belief in God, rebirth, or heaven/hell, as some nastika schools (like Buddhism and Jainism) believe in rebirth and concepts analogous to heaven/ hell, and some astika schools (like Samkhya) are atheistic or non-theistic.