楞伽阿跋多羅寶經註解 1.201

1.201

This asks why there are different names for the Buddha's bodies. The transformation Buddha is the nirmāṇakāya, referring to the hundreds of billions of transformation bodies. The reward-born Buddha is the sambhogakāya for others' benefit, referring to what is seen by other faculties. The tathatā Buddha is the dharmakāya, referring to the essential nature being suchlike and not different. The wisdom Buddha is the sambhogakāya for self-benefit, referring to one's own practice of causes culminating in the fruit, where the wisdom of initial awakening unites with inherent awakening, hence called "wisdom".