Minecraft and it's Realms

So I was of course watching a person play Minecraft in the nether and he was talking about something interesting about if you were to dig up all the way to the top would it be never ending ( Quick shout-out to The Librarian on YouTube) And I remember in early Minecraft that if you dug up all the way in the Nether you would encounter bedrock and if you dug all the way down in the Overworld you would also encounter bedrock so bed rock must be the separation between the two realms right? No, because if you break bedrock in the Overworld you would go into the void and so I thought it would be the plane of existence that separates the realms but then it hit me the void houses the Ender dragon and Enderman but it's not called the void it's called the End, so it would be where nothing exist besides the Enderman and Ender dragon and when you kill the ender dragon the inhabitants of the end all die and it just leaves the floating Chunk of Endstone.