separation vs group action

separation and group action both are nouns.

Word	Noun	Adjective	Verb	Adverb
separation	Yes	No	No	No
group action	Yes	No	No	No

As nouns, group action is a hypernym of separation; that is, group action is a word with a broader meaning than separation:

separation (noun)	group action (noun)
the social act of separating or parting company	action taken by a group of people
the act of dividing or disconnecting
(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