master plan vs plan

master plan and plan both are nouns.

Word	Noun	Adjective	Verb	Adverb
master plan	Yes	No	No	No
plan	Yes	No	Yes	No

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

Other hypernyms of master plan include program, programme.

master plan (noun)	plan (noun)
a long-term outline of a project or government function	scale drawing of a structure
	a series of steps to be carried out or goals to be accomplished
	an arrangement scheme

master plan (verb)	plan (verb)
	make plans for something
	have the will and intention to carry out some action
	make or work out a plan for; devise