congelation vs hardening

congelation and hardening both are nouns.

Word	Noun	Adjective	Verb	Adverb
congelation	Yes	No	No	No
hardening	Yes	No	No	No

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

congelation: the process of congealing; solidification by (or as if by) freezing
hardening: the process of becoming hard or solid by cooling or drying or crystallization

Other hypernyms of congelation include curing, set, solidification, solidifying.

congelation (noun)	hardening (noun)
the process of congealing; solidification by (or as if by) freezing	the act of making something harder (firmer or tighter or more compact)
	the process of becoming hard or solid by cooling or drying or crystallization
	abnormal hardening or thickening of tissue