Johnny asked: “So, manō viññāna is synonymous to kamma viññāna. Does it mean vipāka viññāna can never be a form of manō viññāna?”
Manō viññāna can be vipaka viññāna OR kamma viññāna.
– Vipāka viññāna can be ALL SIX types: They arise via our six senses when a ārammana comes in via the six sense faculties: eyes, ears, nose, tongue, body, and the mind, called cakkhu, sōta, ghāna,jivhā, kāya, and manō viññāna. Those six arise via “cakkhuñca paṭicca rūpe ca uppajjati cakkhuviññāṇaṃ.” through “mananñca paṭicca dhamme ca uppajjati manoviññāṇaṃ.”
– Kamma viññāna can ONLY be mano viññāna. Kamma viññāna arise via “sankhāra paccaya viññāna.“ Those are manō viññāna generated in a PS cycle starting with “avijjā paccayā sankhāra.”
See, “Viññāna – What It Really Means.”
As I said, one needs to understand the recent series of posts given in the above comment.