“There are many kinds of Pralaya, but three chief ones are specially mentioned in old Hindu books:
The first is called NAIMITTIKA, “occasional” or “incidental”, caused by the intervals of “Brahma’s Days”; it is the destruction of creatures, of all that lives and has a form, but not of substance which remains in status quo till the new DAWN in that “Night”.
The other is called PRAKRITIKA – and occurs at the end of the Age or Life of Brahma, when everything that exists is resolved into the primal element, to be remodeled at the end of that longer night.
But the third, Atyantika, does not concern the Worlds or the Universe, but only the individualities of some people; it is thus individual pralaya or NIRVANA;
after having reached which, there is no more future existence possible, no rebirth till after the Maha-Pralaya.
The latter night, lasting as it does 311,040,000,000,000 years and having the possibility of being almost doubled in case the lucky Jivanmukti reaches Nirvana at an early period of a Manvantara, is long enough to be regarded as eternal, if not endless.
The Bhagavata-Purana (12.4.35-36) speaks of a fourth kind of pralaya, the Nitya or constant dissolution, and explains it as the change which takes place imperceptibly in everything in this universe from the globe down to the atom – without cessation.
It is growth and decay (life and death).”
H. P. Blavatsky
The Mark Of God: Understanding Your "I AM Presence" 