Vedanta Advaita teachings on the subject of the ultimate experiences of Oneness (i.e. samadhi) are quite different from the Buddhist teachings. The main difference, as far as I can see, is that the Buddhist teachings (Dzogchen and others as well) affirm the non-self or anatta natural reality whereas Vedanta insists on the base “I am” (Aham Brahmasmi) reality.
Both are valid, of course. To me, however, the “I am” presence, has become like any other movement in the Mind: impermanent and with no base whatsoever.
Rigpa as per fellow Buddhist, quote taken from a closed FB group
( Mahasiddhas, Mahamudra & Dzogchen >> )
“The ultimate nature of all sentient beings is said to be pure, all-encompassing, primordial clarity or naturally occurring timeless clarity. This intrinsic clarity has no form of its own and yet is capable of perceiving, experiencing, reflecting, or expressing all form. It does so without being affected by those forms in any ultimate, permanent way.
The analogy given by Dzogchen masters is that one’s nature is like a mirror which reflects with complete openness but is not affected by the reflections, or like a crystal ball that takes on the colour of the material on which it is placed without itself being changed. The knowledge that ensues from recognizing this mirror-like clarity (which cannot be found by searching nor identified) is what Dzogchenpas refer to as rigpa.”