Wolf3d is an evolution of Hovertank 3D, which had flat shading for walls, floors, and ceilings. Wolf3d then has textured walls but still flat shading on the floors and ceilings. Some other games came out after Wolf3d that had textures floors and ceilings while id worked on Doom.
Doom not only had textured everything, but also stairs. Trick was, you couldn't develop a level that had a hallway going over another hallway. Not enough computer horsepower yet to pull that off. This is sometimes called "2.5D".
Quake brings everything together. Everything's texture mapped, your levels have true height with things built over other things, and the character models are even fully 3d rendered.