According to Osho, the Rajneesh International Meditation University (RIMU) is an educational body that teaches about meditation—producing teachers, scholars, and degrees—while the Rajneesh Academy is existential and experiential, giving you direct realization through suitable, often cathartic, methods. The Academy also confers titles (siddha, arihanta, acharya) that reflect how realized meditators express their awakening.
RIMU teaches facts about meditation; the Academy helps you really meditate and change.