Zoning
Dividing space by function rather than by enclosure — using a rug, a level change, an open divider, a pool of light or furniture orientation to say 'different place' without building a wall. A Subtract move: it keeps the separation a wall would give while removing the wall's cost.
Separation without a wall
A wall costs floor, light, sightline and a door swing, and is fixed. A zone costs none of those and re-zones in an afternoon. Layer two or three cues for a strong, wall-free division.