the comment you are replying to already explains that people sometimes use the term 'dispersion' in that way, but puts it in a broader context:
> but it's true that from time to time people do use the term 'dispersion' to refer to separating light into individual frequency components with a diffraction grating. it just isn't the normal meaning, and it isn't one i'd seen before
> In optics and in wave propagation in general, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency;[1] sometimes the term chromatic dispersion is used for specificity to optics in particular. (...) In optics, one important and familiar consequence of dispersion is the change in the angle of refraction of different colors of light
diffraction gratings do not in any way depend on this phenomenon; they just replicate the consequence through a different mechanism. so where dekhn said, 'The fundamental physical mechanism is known as "dispersion"', linking to the same page i linked above explaining the mechanism that diffraction gratings do not use, they were mistaken
Dispersion is the result, refraction and diffraction are ways that it can happen.
> The grating acts as a dispersive element.
https://en.wikipedia.org/wiki/Diffraction_grating