coup d'etat vs group action

coup d'etat and group action both are nouns.

Word	Noun	Adjective	Verb	Adverb
coup d'etat	Yes	No	No	No
group action	Yes	No	No	No

As nouns, group action is a hypernym of coup d'etat; that is, group action is a word with a broader meaning than coup d'etat:

coup d'etat: a sudden and decisive change of government illegally or by force
group action: action taken by a group of people

coup d'etat (noun)	group action (noun)
a sudden and decisive change of government illegally or by force	action taken by a group of people