hardening vs natural process

hardening and natural process both are nouns.

Word	Noun	Adjective	Verb	Adverb
hardening	Yes	No	No	No
natural process	Yes	No	No	No

As nouns, natural process is a hypernym of hardening; that is, natural process is a word with a broader meaning than hardening:

hardening: the process of becoming hard or solid by cooling or drying or crystallization
natural process: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of hardening include action, activity, natural action.

hardening (noun)	natural process (noun)
the act of making something harder (firmer or tighter or more compact)	a process existing in or produced by nature (rather than by the intent of human beings)
the process of becoming hard or solid by cooling or drying or crystallization
abnormal hardening or thickening of tissue