separation vs severance

separation and severance both are nouns.

Word	Noun	Adjective	Verb	Adverb
separation	Yes	No	No	No
severance	Yes	No	No	No

As nouns, severance is a hyponym of separation; that is, severance is a word with a more specific, narrower meaning than separation:

Other hyponyms of separation include breach, break, falling out, rift, rupture, break.

separation (noun)	severance (noun)
the social act of separating or parting company	the act of severing
the act of dividing or disconnecting	a personal or social separation (as between opposing factions)
(law) the cessation of cohabitation of man and wife (either by mutual agreement or under a court order)
sorting one thing from others
the distance between things
coming apart
the termination of employment (by resignation or dismissal)
the space where a division or parting occurs
the state of lacking unity