The planes of The Elder Scrolls: An overlap of layers
You might've heard that the Planes exist in a structure of layers, where, say, Oblivion is on the outside of Nirn. This is true but, all the planes are infinite. So, how can one infinite mass exist within another? It's simple, or maybe not. Each plane occupies the same physical space insofar as an infinite thing can occupy a space, which means all planes are in the same location. When you're on Nirn, and if you go to Mehrunes Dagon's plane Deadlands (iirc) through an Oblivion Gate you'll end up in the same place every time. Where you enter a plane directly corresponds to where you appear on/in that plane, and to take this further?
Let's say you can traverse the planes at will without any need for gates or voidships or anything except your own Belief. You will still need to go to a point where you are at least near to where you want to be on your destination plane. For an example? You want to go to Sovngarde, which is (or should be) somewhere in Aetherius. To get there, you'd first need to go to the location on Nirn where, on Aetherius, Sovngarde is, then you could simply Believe yourself there.
Now, let's look at void travel.
Void travel is the act of traversing the Void, or Oblivion (they are one and the same and by Oblivion I'm not talking about its sixteen major planes and countless minor ones), and to do this, you'll need something to propel you through it. A voidship. Travel through the Void is possible without one, as I've written about before, however having one is easier than not. For an overview of my thoughts on Voidships and void travel see my addition to this post.
Building on both of these concepts, void travel is the act of going to a place on your current plane (or rather lack thereof because the Void... is complicated), and once there you Believe yourself on another plane. It's that simple. Or possibly not.
TL;DR: planes exist in the same space and you can switch between them at will if your Belief is strong enough.
I hope this explanation isn't too confusing; I'm not the best at laying out my thoughts in a clear way.












