strategy vs plan of action

strategy and plan of action both are nouns.

Word	Noun	Adjective	Verb	Adverb
strategy	Yes	No	No	No
plan of action	Yes	No	No	No

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

strategy (noun)	plan of action (noun)
an elaborate and systematic plan of action	a plan for actively doing something
the branch of military science dealing with military command and the planning and conduct of a war