possible vs possible action

possible and possible action both are nouns.

Word	Noun	Adjective	Verb	Adverb
possible	Yes	Yes	No	No
possible action	Yes	No	No	No

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

Other hypernyms of possible include opening, possibility.

possible (noun)	possible action (noun)
something that can be done	a possible alternative
an applicant who might be suitable

possible (adjective)	possible action (adjective)
capable of happening or existing
existing in possibility