More important than whether or not Peter Brown or Bentinho Massaro is teaching Dzogchen, is to understand the difference between Advaita and Buddhadharma or Dzogchen.
If you understand the differences you'll be able to discern and distinguish by yourself. If you do not understand the difference, it is highly likely that you yourself are in danger of holding on to an erroneous view or understanding, and as you practice and experience more, the more easily you can get stuck on such views as a made-belief view becomes your 'reality' (appears as reality). Then it will be very difficult to get out of it. Unless you have very good guidance but even then, it takes time...
Maybe worthy of a separate thread, but perhaps you could attempt a breakdown of the differences for us, Xabir? Your post alludes to you having navigated this difficult territory. I personally haven't studied enough Advaita to make any attempt at accurate comparisons or contrasts, but I'd appreciate an educated summary from someone who isn't taking the trendy approach of conflating the two.
I just read one of Peter Brown's article, which is quite good in some ways and points to the immediate radiance of all senses without subject-object division and objectification and also points to the spell of karmic traces or what he calls the 'mechanism of imagination, interpretation' (what he calls - http://www.theopendoorway.org/yoga.html
) - but it is still under the framework of what I call "substantial nondualism", which is not the same as having deconstructed Subject/Self via insight (anatta) but rather seen as an undivided reality (an inherently existing Self that is nonetheless indivisible, inseparable, from all its manifestation). This substantializing of Clarity is another form of the functioning of karmic traces or "mechanism of imagination, interpretation" but it is very difficult to "see" - it appears as one's reality, the karmic traces are completely manifest as one's entire experience like a dream that seems very real so one is unable to tell, it is a blinding and powerful magical spell (the spell that conceives of inherently existing self and phenomena).
There comes a time when by self-inquiry, or other methods, that one is led to a direct immediate apprehension of the very Presence of one's Consciousness, the very realness of Existence, of luminosity.... where Consciousness/Awareness/Unfabricated Clarity in its glory and bliss draws complete attention onto itself without any extra thoughts and there is direct realization and complete certainty of one's luminous essence. There is direct realization of the Luminous Essence as the very Pure Presence or Consciousness itself that is more real, more certain and undeniable than anything. One touches the very core of consciousness itself. This is actually a correct realization and concerns the luminous clarity aspect of our Buddha-nature. The problem is not with the direct apprehension of the Luminous essence itself - the problem is that after that moment, due to ignorance and failure to realize the empty nature of luminous clarity, it is immediately being reified and wrongly understood, so it turns into a transcendental, metaphysical Self (with the capital 'S' in contrast to the egoic small letter 's' small self) behind everything. This metaphysical Self is seen as the Ground of Being - the substratum or container from which all phenomena arise and subside to, leaving the noumenon itself unaffected and unchanged, like the depths of the ocean. It is seen as an ultimate Source from which all objects owe its existence to - like the Sun and the reflected planets/objects in space.
When there is complete certainty of Pure Knowing-Presence/Beingness, which is at first the direct realization of the luminous presence of the formless aspect of mind, one later investigates all the other sense fields, penetrate any illusions of a subject-object division until one sees everything as the manifestation of an undivided field of awareness without any objects (apart from being the non-objective expressions of field of consciousness itself, i.e. All is Self).
Luminous essence is now no longer seen dualistically as in "I am I/Consciousness is Consciousness but everything/phenomena is external to consciousness/Consciousness is the eternal witness of phenomena". Rather than conceiving of Consciousness as a dualistic witness behind everything, consciousness is then seen as the source and substance from which everything manifests in and AS that consciousness itself, and consciousness is both the ocean (noumenon) and its waves (phenomena). Even though the view of subject-object duality may be seen through (but not really - it is an incomplete dissolving of subject-object view) in an insight into non-duality and the radiant clarity experienced in all senses, the view of inherency continues so one still conceives of Consciousness as truly and inherently existing as a metaphysical absolute or source and substance which is expressing indivisibly as every sight/sound/etc without subject-object division (this is where Peter Brown is at). This causes a continual subtle referencing back to a Self by subsuming all experience to be Self (as expressions of Self). I call this phase "one mind". This is the furthest that Advaita (both neo and traditional) has went to. Despite experiencing and realizing undivided clarity, there is strong attachment to a metaphysical, changeless, independent, inherently existing Absolute.
Then hopefully with direct contemplation into no-self (with help of pointers and teachings, such as bahiya sutta), there can be a breakthrough into the seal-insight of anatta: always already, in hearing just sound hearing (hearing is the sound!) never a hearer, so complete, so gapless, the entirety of your reality (except there is no 'you') is fully just sound... in seeing only always just scenery, never a you seeing or seer... your entire reality is only and completely this whole universe (experiential universe, a.k.a. the seamless total exertion of seeing-hearing-smelling-tasting-touching-thinking as one whole marvelous limitless foreground activity giving its best to make this entirety) seeing itself, tasting itself, touching itself. It's like the behind (self/Self) is totally lost (it never existed! but certainly was a very strong delusion until seen through) and what's left is only the limitless and brilliant in front (whatever's appearing) which is your entire reality but there is no more in front or behind or up or down because there is no more a reference of a center or a boundary. Even this is not the end and there can be further deconstruction, and penetration, into the emptiness and non-arising of phenomena.
After realization of no-self (anatman), one is freed from that "dual and inherent spell", there is no denial of luminous clarity and instantly one is in a non-dual state in six entries and exits, where scenery, sound, thought, scent is radiant (vivid, clear, bright, aware, alive) as itself without ground and references. There is no skewing to the luminosity of formless mind nor is non-dual clarity reified into a "All-Self" like in One Mind. One understands, as Ted Biringer said, "...According to Dogen, this “oceanic-body” does not contain the myriad forms, nor is it made up of myriad forms – it is the myriad forms themselves. The same instruction is provided at the beginning of Shobogenzo, Gabyo (pictured rice-cakes) where, he asserts that, “as all Buddhas are enlightenment” (sho, or honsho), so too, “all dharmas are enlightenment” which he says does not mean they are simply “one” nature or mind."