Dhamma (Pali) realms are planes of existence. It is apparent that the ten dharma (Sanskrit) realms of the Mahayana sutras are simplifications of the thirty one dhamma realms of the Theravada suttas.
The Pali Canon suttas divide the planes of existence into the sense-sphere realm (where the beings are captivated with sense desire), the fine-material realm, and the immaterial realm.
The four lowest realms of the Mahayana school, from the bottom up, are the hell realm, the hungry ghost realm, the animal realm and the realm of asuras, the combative titans, in that order. The lowest three are the evil realms.
The Pali Canon switches the order of the middle two, ordering the realms as the hell (31), animal (30), hungry ghost (29) and asura (28) planes of existence, and declares that all four of them are evil destinations.
Both schools agree that the human dharma realm (27) is the fifth from the bottom and thus a good plane of existence.
Both schools also agree that the sense-sphere realm includes at least one heavenly realm above the human realm, but the beings of that realm are imperfect enough to nonetheless belong to the sense-sphere realm.
However, instead of one heavenly realm in the bottom six realms (Hakuin’s “six worlds” that we “endlessly circle”), the Pali Canon recites that there are six heavenly realms in the sense-sphere realm. From the bottom to the top, they are the gods under the Four Great Kings (26), the gods of the Thirty-three (25) (which may explain the name of the famous San-Ju-San Gen Do in Kyoto, san-ju-san meaning “33”), the Yama gods (24), the gods of the Tusita heaven (23) (where Bodhisattvas reside before final birth, and thought to be the heaven of the Bible), the gods who delight in creating (22), and the gods who wield power over others’ creations (21).
So the lower six realms of the Mahayana school coincides with the lower eleven realms of the Theravada school, there being an extra five heavens in the latter.
The beings of the fine material plane of existence are no longer subject to sense desire and they have left the lower six realms, the sense-sphere realm, never to fall back. As the name of this collection of realms implies, however, the beings are free of the gross material world but they still have some connection to the material world and have not achieved anuttara samyak sambodhi, total liberation.
The fine-material realm has sixteen planes of existence, three of which are planes associated with the first jhana, three of which are associated with the second jhana, three of which are associated with the third jhana, two of which are associated with the fourth jhana, and the final five of which are associated with The Pure Land, referred to in the Pali Canon as The Pure Abodes.
Bhikkhu Bodhi calls these sixteen realms the “objective counterparts” of the four jhanas. Accordingly, development of the first jhana to an inferior degree leads to rebirth among Brahma’s Assembly (20), middling development of the first jhana leads to rebirth among the Ministers of Brahma (19), and superior development of the first jhana leads to rebirth among the Maha Brahmas (18).
In the same inferior-middling-superior development way, development of the second jhana leads to rebirth among the gods of Limited Radiance (17), Immeasurable Radiance (16), and of Streaming Radiance (15).
Likewise, development of the third jhana leads to rebirth among the gods of Limited Glory (14), of Immeasurable Glory (13), and of Refulgent Glory (12).
Superior development of the fourth jhana leads to rebirth among the gods of Great Fruit (11). However, if the fourth jhana is developed with a desire for insentient existence (which seems to be a contradiction in terms), then it leads to rebirth among non-percipient beings (10) “for whom consciousness is temporarily suspended” to quote Bhikkhu Bodhi. Apparently, since the total number of fine-material realms is sixteen, this rebirth among the gods of Great Fruit counts as two realms, depending upon whether or not the fourth jhana was developed with a desire for insentient existence or not.
The final five realms of the sixteen realms of the fine-material realm are the five Pure Abodes, the realm of the non-returners. They are, from bottom to top, the Aviha (9), the Atappa (8), the Sudassa (7), the Sudassi (6), and the Akanittha (5). The lifetime of the beings in these Pure Abodes increases “significantly in each higher plane.”
The eleven sense-sphere realms and the sixteen fine material realms total twenty seven so there are four more. These four are in the immaterial realm and are the “objective counterparts” of the four immaterial attainments. These four highest realms are named accordingly: The realms of infinite space (4), infinite consciousness (3), nothingness (2) and neither-perception-nor-non-perception (1).
Again, Nirvana/Nibbana is not counted as the first dharma realm; it is not a dharma realm under the teachings of the Buddha as recorded in the Pali Canon.
Thus we see that development of the four jhanas leads to rebirth in the fine-material realm whereas development of the four immaterial attainments leads to rebirth in the immaterial realm. And that development of all four jhanas and all four immaterial attainments falls short of Nibbana.
We can also see the different rankings of a Bodhisatta/Bodhisattva in the Theravada and Mahayana schools. In the older school, the Bodhisatta merely resides in the Tusita heaven which is one of the heavens of the six lower realms. Therefore, a Bodhisatta is eligible for rebirth in any one of the six worlds. In the Mahayana school, a Bodhisattva resides in the second highest dharma realm, only one step down from the dharma realm of the Buddhas, and is clearly not subject to rebirth in an evil dharma realm. The Bodhisattva chooses rebirth in the human dharma realm due to compassion for humans and other sentient beings.
As such, the Mahayana school holds a Bodhisattva in higher regard than a Buddha. A Buddha exits from all dharma realms. The Bodhisattva refuses to do so until the hells are empty and all sentient beings enter into Nirvana.
As an unenligthened sentient being, neither explanation of Bodhisattavas makes sense to me. If Nibbana is outside of all dharma realms as taught by the Theravada school, then reality has a split formed in it, i.e., there is a dichotomy. If Nirvana is the first dharma realm and the beings who attain it are no longer beings at all and cannot re-enter any other dharma realm, as taught by the Mahayana school, the dichotomy again appears.
So I prefer to look at the dhamma realms as not being clearly defined and as extending infinitely in both directions from the crude to the subtle. No hottest hell, no best heaven. No bottom at one end and no top at the other.
So if we sit in tranquil wisdom and reach the realm of neither perception nor non perception, and then fade away into Nibbana, never to be re-born into “existence” again, what if that final cessation, that liberation from existence is merely entry into the lowest Nibbana…