Spatial hierarchy is what makes a well-designed home feel "right" without you being able to name why. It's the invisible logic that says: this is the primary space, that's the secondary space, this room is for hosting, that one is for sleeping, this seating area is for conversation, that one is for reading. Every space has a defined role and the design supports it.
Designers signal hierarchy with material moves. The primary space gets the best light, the most expensive material, the highest-quality furniture, the strongest focal point. Secondary spaces are quieter — same palette and material family but less articulated. Transitional spaces (hallways, stairs) are quietest of all, calibrated to lead you toward the primary spaces rather than compete with them.
When hierarchy is broken — when every room shouts equally loud, or when a back hallway gets the most expensive lighting — the home feels confused. When hierarchy is clear, the home is easier to live in even if you can't articulate the principles at work.