Design Nomenclature / Form & Geometry
World space
Also called global space, scene space, world coordinates
The single global frame every object resolves into — the scene's origin and axes. A vertex's world position is its local position run through its own transform and then every ancestor's, in order, up the hierarchy. Distances, physics, and export coordinates all live here; almost nothing is authored here.
In practice
Which axis is up is a per-application convention, not a fact: Z-up in CAD and Blender, Y-up in Maya and most engines. That single disagreement accounts for a large share of all import failures.