Sufi: Experiences like dreams where you see things which nobody else sees. But mystics have experiences like they have visions of God, they hear the voice of God. Vedanta says there's a distinction between a dream and a spiritual experience. "The genuine mystic experience is possible only for the mystic"
Swami Sarvapriyananda teaches one of the shortest and most profound upanishads accompanied by Gaudapada's Karika. This lecture covers Karika 1-5.