Preface To Walls: Ceilings & Floors

I googled this: "How is a wall different than a floor or a ceiling?"  All the responses involved doing similar things (like soundproofing) to all three parts, rather than even venturing a guess at the differences between the three.

This is intolerable.

Imagine, if you will, a world in which everything is turned on its side.  In such a world, two of our walls would become the floor & the ceiling, while the floor & the ceiling would unceremoniously become walls.

How would each part adjust to its new circumstance?  I can think of a few troubling scenarios.

First of all, doors, which are commonly found mostly in walls, would be a little useless if now on the floor (unless there's a basement).  Were doors to end up on the ceiling, well, it would make answering the door even more of a chore than it currently is.

Furthermore, cellar doors or trap doors, or even skylights, will probably make poor door choices for the new world which is on its side.

Here's another thing: plumbing.  I don't know much about plumbing but it does seem to me that the pipes that I assume are what people talk about when they talk about plumbing would not increase one's property value should they be sticking boldly out of the side of the house rather than into the ground where they (again, I am assuming this) connect in a fascinating way to the sewer.

& I bet you've thought of this one: in larger buildings, which is to say those with many floors, or "stories," the walls when the building is on its side will be much, much larger than the ceiling & floor.  This would cause places where building grew up instead of out because of space restrictions to become completely clogged, with no room for bike lanes or promenades or any of the things that make city life worth tackling.

I am no architect nor private detective so I can't begin to truly understand the severe differences between floors, ceilings, & walls, & it bothers me like bug bite that someone with more know-how hasn't tackled this issue before.

It's your time, young genius!  Do it quickly, though - one never knows when the world will be turned on its side!