I think its more murky than that.

There was a whole story arc about mutant growth hormone, which was derived from skin cells scraped off people like the Owl and other supers.

This MGH gave humans temporary mutant powers, and cites its origin as the X-Gene.

Confusingly though, it still tries to draw an arbitrary distinction between inherited mutants and somatic ones.

Origin

While it is most of the time extracted from mutants, it can also be extracted/synthesized from other super-powered individuals, but the source of their superpowers must alter their genetic make-up. For example, the Owl or Spider-Woman are not mutants, but their powers come from genetic mutations, and they were both used as MGH sources.

My understanding of this, is that anyone who has a non-fatal mutation of their X-factor gene develops mutant powers and abilities and, if permanent, becomes a mutant.

“Traditional” mutants inherit the X-factor, and are mutants from birth. That’s the only distinction I can see, and seems like a bit of a weak distinction tbh.