stationery seller vs merchant

stationery seller and merchant both are nouns.

Word	Noun	Adjective	Verb	Adverb
stationery seller	Yes	No	No	No
merchant	Yes	No	No	No

As nouns, merchant is a hypernym of stationery seller; that is, merchant is a word with a broader meaning than stationery seller:

stationery seller: a merchant who sells writing materials and office supplies
merchant: a businessperson engaged in retail trade

Other hypernyms of stationery seller include merchandiser.

stationery seller (noun)	merchant (noun)
a merchant who sells writing materials and office supplies	a businessperson engaged in retail trade