Krishna is the source of all incarnations/expansions/planery expantions. Lord Krishna is the original Lord Vishnu.
Buddha is also an incarnation of Lord. But such incarnations are not considered to be very advanced in Vedic knowledge(Lord does His own ways). There was a special purpose of Buddha incarnation. So called brahmanas of that time were slaughtering animals on the names of sacrifices given in the Vedas. So Lord incarnated to take away people by preaching Non-violence.
Buddha asked peop