Nirvikalpa, Savikalpa and Sahaja Samadhi. What’s the Difference?

Some books say nirvikalpa-samadhi is the best type of mind-state to assimilate Self-Knowledge. Others argue it's savikalpa-samadhi. While Ramana Maharshi says it's sahaja-samadhi. Clarify please…

Nirvikalpa-Samadhi

Firstly, nirvikalpa-samadhi has two definitions:

1. Yogic definition (as explained in Patanjali Yoga Sutra): This is the one we'll be describing below. 
2. Advaita Vedanta definition: Nirvikalpa means the intellect no longer has opposing thoughts (doubts) regarding the nature of “I”. So basically it's referring to a wise person (jivanmukta) who enjoys a permanent understanding of one's True nature.

Answering Patanjali Yoga Sutras' Nirvikalpa-Samadhi…

Self-knowledge cannot be assimilated during nirvikalpa-samadhi because the buddhi (intellect) has basically resolved into a state of temporary dormancy within the causal body (karana-sharira).

Why can't self-knowledge be assimilated? Because intellect is all you have to discern or make sense of any experience. To extract insights and to assimilate them into permanent understandings that percolate through your entire being, in day-to-day living.

Furthermore, the buddhi is intwined with the memory (which is required to remember and contemplate later) and the ahamkara (I-sense) — the mechanism that localizes any learning to a single body-mind complex. 

Meaning when buddhi resolves, so does the memory and ahamkara resolve. Meaning, upon entry into nirvikalpa — the meditator hasn't remember nor understood anything, because there was no meditator or thinker or appreciator or learner (ahamkara) present in the nirvikalpa.

It's as good as a stranger having it, whose unable to pass on the benefits onto you (the meditator).

Moreover, during nirvikalpa, the intellect abides in a single, subtle, unmodified thought (“awake” to the anandamaya-kosha's bliss).

While this thought does offer a glimpse into our limitless nature — the mind perceiving it is in a state no different than dreamless sleep.

Though the “experience” of limitlessness is had — the knowledge is not consciously recognized, hence there's nothing valuable or long-term to take back into the ordinary waking experience that makes up majority of our life.

In short: The intellect is the instrument of knowledge, and thus if the intellect is not functioning, knowledge does not take place.

Savikalpa-Samadhi

In Savikalpa-samadhi — the intellect, memory and I-sense have not resolved into the causal-body.

They are available to the meditator, thus the meditator is able to consciously appreciate one's vast nature — temporarily devoid of sense of smallness or being contained to a single body-mind complex.

Upon return to normal state — the meditator can further reflect, learn and transform one's life by the insights, since the entire experience was captured by the memory.

Savikalpa-samadhi can occur while one is transacting “business” with the world, but it is more likely to occur during sessions of formal or “seated” meditation.

Furthermore, Savikalpa-samadhi is the ideal platform for self-inquiry, and it was in a state of savikalpa-samadhi, in fact, that Ramana Maharishi had his famous near-death experience; the epiphany by means of which he realized the Self.

Sahaja-Samadhi

Once the knowledge afforded through the experience of savikalpa-samadhi has been assimilated — then one is able to recognize and apprciate the underlying nirvikalpa nature of Awareness that is one’s true identity, even while engaged in one’s daily activities.

This stage is called sahaja-samadhi or nirvikalpa-samadhi (Advaita Vedanta definition as explained above; not referring to Yogic definition). Otherwise called a jnani or wise-person.

This is the state that characterizes the jiva’s life within the context of the apparent reality after the assimilation of self-knowledge.