separation vs breakup

separation and breakup both are nouns.

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

As nouns, separation and breakup are synonyms defined as:

Other synonyms of separation include detachment.

separation (noun)	breakup (noun)
the social act of separating or parting company	the termination or disintegration of a relationship (between persons or nations)
the act of dividing or disconnecting	coming apart
(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