schism vs severance

schism and severance both are nouns.

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

As nouns, severance is a hypernym of schism; that is, severance is a word with a broader meaning than schism:

schism: the formal separation of a church into two churches or the withdrawal of one group over doctrinal differences
severance: a personal or social separation (as between opposing factions)

Other hypernyms of schism include breach, break, falling out, rift, rupture.

schism (noun)	severance (noun)
division of a group into opposing factions	the act of severing
the formal separation of a church into two churches or the withdrawal of one group over doctrinal differences	a personal or social separation (as between opposing factions)