So a lot happened in the Revelation's chapter, and all this talk about realities, gates and gods is probably really confusing so I hope I can try and explain it for you.

First like the title suggests this is a cross section of reality, so take what this picture is and copy an infant number of times backwards, forwards, any direction really and it's still going to represent the same thing.

Secondly, what I consider a reality is the location in which mortal beings reside, so the Mortal Realities listed above are entire universes, galaxies and so on.

Third, Not every reality is the same, imagine this thought experiment, or do this experiment in person if you can. Take a mirror and hold it so that it reflects an image and another mirror. When this is done it creates an infinite loop, but that isn't quite what I want you to focus on. Focus on the object you place between those two reflections, as you look down these repeated reflections the object distorts, shrinks or blurs. Imagine that object as earth and each reflection a distortion of the original earth. So Mortal Reality 1 and Mortal Reality 2 can be near identical in form and presence but history could be different, locations and names could be distorted, even written Language could mean wildly different things than what were used to, like the word baby, that could mean adult in different reality and vice versa. But Mortal Reality 1 and Mortal Reality 5 could be vastly different, where Earth for instance, could cease to be a real place, humans could be a strange alien race instead of what we are, and so on.
=======>Now this last Part might be a little bit hard to understand, but now imagine this infinite loop in the shape of an orb, so that distortions aren't merely a linear path anymore, and that is how you comprehend the nature of realities, in my book at least.

Fourth, Definitions

Spirit Realm: This is the reality between the heaven and the underworld where transcended races, as well as supernatural spirits, and elements reside.

Veneer: This is an all essence the cytoplasm of a cell, it's the space that divides the heavens and the underworld from one another, holding everything in place, as well as act as a through fare for the Gods of Creation... This is their "home".

Heaven: The place where Angels and good natured souls go when they die.

Underworld: The place where Demons and the Damned go when they die.

Essence: The primordial nature of Heaven, it's said that that this is where Mortal souls come from.

Abyss: The primordial nature of the Underworld, it is said to be the end of all Mortal things.

(Gates) These are the dams created by the gods of creation to regulate magic, how much comes in and or leaves one reality at any given point in time. Because this can be one of the few difference between realities, some can have magic, some might be destined to have magic, while some are never meant to obtain any. However they serve a second purpose, much like Faster than Light Travel space lanes, once opened, Mortal Races if they have the know how can travel between realities, as long as the gods allow it and or the reality already has the Gates open to travel. So transcended beings can interact and travel to each other's worlds or live in the spirit world.

(Please tell me if something doesn't make sense, I'll try and explain it as best as I can)