Today, I’ve been thinking about the slightly different natures of different question words (and thus, different kinds of ideas they refer to).
Here’s a tentative observation:
“What” and “who” are words we use to refer to unknown or abstract things or people. This means that each of them designates a real or conceptual entity, a thing that somehow constitutes a cohesive whole.
“When” and “where”, on the other hand, designate locations in time or space. On their own, these locations are merely points, directions or vague areas, and do not require cohesion.
Examples will be furnished on demand.

Please furnish some examples.
“what” and “who” are absolute, actors.
“when” and “where” are relative, context.
Relativity is trying to give cohesion to the whole and interoperability. Which means, it is possible to equate the semantic absolute and the relative.
Within the simplest sentence we can apprehend the universe.
In that sense, actors and context are one same thing, it is activity, interactions, energy.