We were discussing this in chat and folks wanted it here for ease of study and discussion.
While every culture and many religions have their own concept of the Realms, the occult tends toward four esoteric realms. The concept of the 4 worlds is thought to originate in the Kabbalist text The Zohar, though writings from Ancient Sumer seem to echo these concepts.
1. World of Emanation (aka Supernatural plane). On this level are the many Gods. When a priest/ess invokes, the divine spirit comes from this world tp make contact with the Astral Body and through it, the physical body. It is important to note that invocation does not include posession, as posession is another form of working that takes over the body whereas invoked deities guide the body.
2. World of Creation (aka Stellar plane). This is where the highest ranking Angels and stellar deities reside. The Astral body may travel here for divinatory, oracular and many other forms of esoteric workings.
3. World of Formation (aka Astral plane). The Astral Body, though Etheric itself, travels here to work magic and journey. Here is the world of the "holy creatures" and the ten lower classes of angels.
4. World of Action (aka Earthly or Mundane plane) where we reside. The Etheric realm or plane is a hyperplane or subplane of the Earthly plane and exists just sideways of ours, so is easily worked with. The Astral Body, including the Chakras, sefiroth and chi are part of the Etheric plane.
When practitioners do visualization, some forms of journeying and meditation, as well as many energy workings, they do so on the Etheric with their Astral Body. The Astral Body, however, may travel to other realms temporarily.
Hopefully, this will create some intereting discussion.