merchandise vs refill

merchandise and refill both are nouns.

Word	Noun	Adjective	Verb	Adverb
merchandise	Yes	No	Yes	No
refill	Yes	No	Yes	No

As nouns, refill is a hyponym of merchandise; that is, refill is a word with a more specific, narrower meaning than merchandise:

merchandise: items for sale to the individual consumer
refill: a commercial product that refills a container with its appropriate contents

merchandise (noun)	refill (noun)
items for sale to the individual consumer	a commercial product that refills a container with its appropriate contents
branded products meant to promote another product, especially films and pop groups	a prescription drug that is provided again

merchandise (verb)	refill (verb)
engage in the trade of	fill something that had previously been emptied