tactics vs plan of action

tactics and plan of action both are nouns.

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

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

tactics (noun)	plan of action (noun)
a plan for attaining a particular goal	a plan for actively doing something
the branch of military science dealing with detailed maneuvers to achieve objectives set by strategy