If you are asking this question from stand point of a seeker who is already on the path then it needs elaborate answer of which most of other readers would not be able to comprehend much. And answering this question considering it to come from someone who is just inquisitive without any spiritual experience whatsoever the answer would lack depth and substance. So I am answering it for both the categories of people..
a. Those who are on the journey and seeking experiential understanding and
b. the one’s who are engaged in intellectualization of the TRUTH.
Nonetheless, unfortunately both the answers shall become just intellectual fodder for everyone who hasn’t had a direct experience of at least Enlightenment irrespective of whether they fall under a. or b. Both ‘Enlightenment’ and ‘Nirvana’ are surely not the things of explanation but experience.
WHAT IS ENLIGHTENMENT
Some people wrongly associate it to be an intellectual understanding or a physical sensation such as experience of ‘Nothingness/Emergence of Boundless Light etc.’ as in so called ‘Samadhi’ or as an experience of energy surge or emotional outburst while so called ‘Kundalini Awakening’. These are just some phases that one experiences in one’s journey towards enlightenment.
Enlightenment is recognition of one’s true nature and individual identity beyond body. It is experience which then becomes ingrained in every atom of one’s being – experience of a peculiar freedom at the level of body, mind and action. In actuality when one gets enlightened his/her world-view and personal identification goes through a paradigm change. Overwhelmingly with this experience of one’s essence being beyond body, mind and other outwardly associations the notion of birth and death fall apart and any suffering, be it in body or mind can be clearly seen as an outwardly phenomenon; not touching or impacting that inner essence called ‘Self’. Therefore ‘Enlightenment’ is recognition (through experience) of a deeper, much truer ‘self’ that is not the part of the ‘outer’. It is truly a blessing and probably the most beautiful experience that one can have as an ‘Individual’.
Yet self-realization or Enlightenment is not Nirvana for the enlightened person still feels separation from others. Such a person continues to experience this outer manifestation as something ‘other than him’. His mind is expanded but still not enough to encompass the whole in it. The enlightenment doesn’t give a seeker the vision of his unity with the cosmic presence that ‘is’. Here one has has experience of one’s ‘oceanic’ nature while still maintaining the identity of a ‘wave’. Nevertheless this person has now risen above the ordinary consciousness and is in touch with a perennial blissful state within whatever be the outer circumstances and actions of body and even mind. Such a person is concerned with the welfare and ignorance of other ‘waves’ for he still sees them as different from ‘self’ yet this state of his can not and should not be undermined. He is much more ‘closer’ to the Truth than the ordinary and therefore he is blessed. He is ‘extra-ordinary’!
WHAT IS NIRVANA OR MOKSHA
So, it should be understood clearly that even beyond enlightenment or self-realization there remain many more levels of experiences of the Truth. The Nirvana is the living experience of ‘the ultimate Truth’.
Although putting Nirvana into words is not possible but closest words to explain but the closest would be like.. Nirvana means ‘There is no other’. The world and I are one without any separation. Such experience would mean the ‘cosmic inclusiveness’ and complete dissolution of personal identity. For a person in Nirvana there is no ‘Nirvana’ for there is nothing that exists beyond ‘self’ or I.
For such a Yogi this infinite cosmic existence is his own play that is happening in this cosmic body, an experience that is beyond individualized body and individualized mind. The whole outside (universe or multiverses as you may like to put it) is me or my body is the experience.. all the time. Shiva Sutra says to this effect “दृश्यम् शरीरम्”.
Since I have quoted a Tantric text it is my duty to further elaborate that as per tantric understanding the true Nirvana (state of being a Shiva) is not possible while still being in this body (physical, astral or causal). While in body for a Sadhaka it is the state of ‘Bhairava‘ and only after dropping this body he becomes ‘Shiva’!
May be I have been able to explain and may be you understood what is the difference but there’s no point – It is not something that can be grasped with mind or intellect. So no intellectualization please!
Come! Experience it.
-Acharya Agyaatadarshan Anand Nath