nationalization vs group action

nationalization and group action both are nouns.

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

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

nationalization (noun)	group action (noun)
changing something from private to state ownership or control	action taken by a group of people
the action of rendering national in character
the action of forming or becoming a nation