enlightenment "certain realease or insight" should not be confused with "rightly awakening".
As for rightly awakening there are generally four stages (which is not a religious definition but actuually) and it's gradual.
In regard of release, see vimutti
- From what is one released?: AN 10.81
- Released through awareness: AN 6.13
- Four kinds of awareness-release: SN 41.7
- Released through discernment: AN 9.44
- Released "both ways": AN 9.45
- The Buddha's question-and-answer session concerning release: Snp ch. 5
Aside of this there are 4 fruis, one could say for stages of awakening: phala, defining with their path magga the eight Noble persons ariya-puggala
Generally it's spoken about 4 stages of awakening:
- the Stream-winner (Sotāpanna)
- the Once-Returner (Sakadāgāmi)
- the Non-Returner (Anāgāmī)
the Holy One (Arahat)
(I) Through the path of Stream-winning (sotāpatti-magga) one 'becomes' free (whereas in realizing the fruition, one 'is' free) from the first 3 fetters (samyojana) which bind beings to existence in the sensuous sphere, to wit:
-- (1) personality-belief (sakkāya-ditthi; s. ditthi),
-- (2) skeptical doubt (vicikicchā),
-- (3) attachment to mere rules and rituals (sīlabbata-parāmāsa; s. upādāna).
- (II) Through the path of Once-return (sakadāgāmi-magga) one becomes nearly free from the 4th and 5th fetters, to wit:
-- (4) sensuous craving (kāma-cchanda = kāma-rāga; s. rāga),
-- (5) ill-will (vyāpāda = dosa, s. mūla).
(III) Through the path of Non-return (anāgāmi-magga) one becomes fully free from the above-mentioned 5 lower fetters.
(IV) Through the path of Holiness (arahatta-magga) one further becomes free from the 5 higher fetters, to wit:
-- (6) craving for fine material existence (rūpa-rāga),
-- (7) craving for immaterial existence. (arūpa-rāga),
-- (8) conceit (māna),
-- (9) restlessness (uddhacca),
-- (10) ignorance (avijjā).
For even more about the stages of release and knowledge see:
Wisdom and the Seventy-Three Kinds of Mundane and Supramundane Knowledge, kindly given by Ven. Bhikkhu Ñāṇadassana.
Best support here for: Into the Stream - A Study Guide on the First Stage of Awakening
Much success! If not possible, the Buddha would not have teached, but a matter of effort and right deeds.
[Note: This is a gift of Dhamma, not meant for commercial purpose or other kinds of low wordily gains by means of trade and exchange]