coat of paint vs primer

coat of paint and primer both are nouns.

Word	Noun	Adjective	Verb	Adverb
coat of paint	Yes	No	No	No
primer	Yes	No	No	No

As nouns, primer is a hyponym of coat of paint; that is, primer is a word with a more specific, narrower meaning than coat of paint:

Other hyponyms of coat of paint include flat coat, ground, primer coat, priming, priming coat, undercoat.

coat of paint (noun)	primer (noun)
a layer of paint covering something else	any igniter that is used to initiate the burning of a propellant
	the first or preliminary coat of paint or size applied to a surface
	an introductory textbook