lunch meat vs luncheon meat

lunch meat and luncheon meat both are nouns.

Word	Noun	Adjective	Verb	Adverb
lunch meat	Yes	No	No	No
luncheon meat	Yes	No	No	No

As nouns, lunch meat and luncheon meat are synonyms defined as:

lunch meat and luncheon meat: any of various sausages or molded loaf meats sliced and served cold

lunch meat (noun)	luncheon meat (noun)
any of various sausages or molded loaf meats sliced and served cold	any of various sausages or molded loaf meats sliced and served cold