Good question, I guess fog is generally all “volumetric” in a sense, fmu of a differentiation, true “volumetric fog” would look like this three.js webgl2 - volume - cloud
Typical in-built scene depth fog
Which can be extended in all types of ways as @trueshko has suggested above, there’s a great thread here…
And then by “screen space” fog I’m referring to more of a shader pass that acts more like a vignette…
Any chance you can give a minimal visual that depicts the effect you’re going for?