phase-out vs discontinuation

phase-out and discontinuation both are nouns.

Word	Noun	Adjective	Verb	Adverb
phase-out	Yes	No	No	No
discontinuation	Yes	No	No	No

As nouns, discontinuation is a hypernym of phase-out; that is, discontinuation is a word with a broader meaning than phase-out:

phase-out: the act or instance of a planned discontinuation
discontinuation: the act of discontinuing or breaking off; an interruption (temporary or permanent)

Other hypernyms of phase-out include discontinuance.

phase-out (noun)	discontinuation (noun)
the act or instance of a planned discontinuation	the act of discontinuing or breaking off; an interruption (temporary or permanent)