severance vs falling out

severance and falling out both are nouns.

Word	Noun	Adjective	Verb	Adverb
severance	Yes	No	No	No
falling out	Yes	No	No	No

As nouns, severance and falling out are synonyms defined as:

severance and falling out: a personal or social separation (as between opposing factions)

Other synonyms of severance include breach, break, rift, rupture.

severance (noun)	falling out (noun)
the act of severing	a personal or social separation (as between opposing factions)
a personal or social separation (as between opposing factions)