priming vs flat coat

priming and flat coat both are nouns.

Word	Noun	Adjective	Verb	Adverb
priming	Yes	No	No	No
flat coat	Yes	No	No	No

As nouns, priming and flat coat are synonyms defined as:

priming and flat coat: the first or preliminary coat of paint or size applied to a surface

Other synonyms of priming include ground, primer, primer coat, priming coat, undercoat.

priming (noun)	flat coat (noun)
the act of making something ready	the first or preliminary coat of paint or size applied to a surface
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