Trailokya has been translated as "three worlds," "three spheres," "three planes of existence," "three realms" and "three regions." These three worlds are identified in Hinduism and appear in early Buddhist texts.
Rūpaloka is the world of form, predominately free of baser desires, populated by dhyāna-dwelling gods, possible rebirth destination for those well practiced in dhyāna.
Arūpaloka is the world of formlessness, a noncorporeal realm populated with four heavens, possible rebirth destination for practitioners of the four formlessness stages.
According to Helena Blavatsky's posthumously published Theosophical Glossary :
Kamaloka is the world of Mara. Kamaloka has, like every other world, its seven divisions, the lowest of which begins on earth or invisibly in its atmosphere; the six others ascend gradually, the highest being the abode of those who have died owing to accident, or suicide in a fit of temporary insanity, or were otherwise victims of external forces. It is a place where all those who have died before the end of the term allotted to them, and whose higher principles do not, therefore, go at once into Devachanic state—sleep a dreamless sweet sleep of oblivion, at the termination of which they are either reborn immediately, or pass gradually into the Devachanic state.
Rupaloka is the celestial world of "form", or what we call "Devachan." With the uninitiated Brahmans, Chinese and other Buddhists, the Rupadhatu is divided into eighteen Brahma or Devalokas; the life of a soul therein lasts from half a Yuga up to 16,000 Yugas or Kalpas, and the height of the "Shades" is from half a Yojana up to 16,000 Yojanas. Esoteric Philosophyteaches that though for the Egos for the time being, everything or everyone preserves its form, yet as Rupadhatu is a purely matter world, and a state, the Egos themselves have no form outside their own consciousness. Esotericism divides this world into seven Dhyanas, "regions", or states of contemplation, which are not localities but mental representations of these.
Arupaloka is a world that is again divided into seven Dhyanas, still more abstract and formless, for this "World" is without any form or desire whatever. It is the highest world of the post-mortem Trailokya; and as it is the abode of those who are almost ready for Nirvana, and is, in fact, the very threshold of the Nirvanic state, it stands to reason that in Anupadhatu there can be neither form nor sensation, nor any feeling connected with our three-dimensional Universe.
