Very interesting firsthand comparison of NDEs and psychedelics:
The Difference Between Drug-Induced Spiritual Experiences & Near-Death Experiences By NDEr Diane Goble
"The difference is brain chemistry is affected by LSD. During a NDE experience, consciousness leaves the brain. Consciousness survives death and is eternal. Having experienced both, I have some expertise.
"During my NDE (40 years ago at age 30, I drowned), I was part of the experience, involved in it, participating in it, one with it. There was never any fear, only overwhelming love and peace. It was more a remembering, it all came back to me, of having done this all before, knowing I was going home, an experience of having complete knowledge of the Whole/Source/God.
"About 15 years later, I tried LSD a few times, also mushrooms and MDMA.
"This was shortly after I found out what I had was called a 'near-death experience.' Before that I didn't know what to call it and never talked about it because I was afraid people would think I was crazy -- or possessed. Then I started reading about other people having similar experiences.
"The psychedelic experiences were as different from my NDE as looking into a fish tank and SCUBA diving around coral reefs in Nassau. The only thing similar was the out-of-body experience and exploring another dimension of the multi-verse. A big difference is between seeing and being. LSD showed me a mechanical, Newtonian universe. Mushrooms more of a fairy land, full of interesting, magical creatures from etheric to earthy, underground. Ecstasy was an exploration of my inner being from a loving perspective. All fun and exotic, but nothing profound, ineffable, meaningful, esoteric like the NDE. I returned with knowledge of particle physics and galactic motion (and I'm no scientist).
"Forty years later, I remember no details from any of about half a dozen psychedelic experiences and every detail, feeling, and emotion from my NDE. It changed the course of my life, my personality, my interests, my beliefs, my future. I know my purpose in this life and I live it. I have no fear of death, I know what happens next! The drugs did nothing but provide a few hours of meaningless entertainment."