scheme vs plan of action

scheme and plan of action both are nouns.

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

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

scheme (noun)	plan of action (noun)
an elaborate and systematic plan of action	a plan for actively doing something
an internal representation of the world; an organization of concepts and actions that can be revised by new information about the world
a schematic or preliminary plan
a statement that evades the question by cleverness or trickery
a group of independent but interrelated elements comprising a unified whole

scheme (verb)	plan of action (verb)
form intrigues (for) in an underhand manner
devise a system or form a scheme for