replenishment vs refilling

replenishment and refilling both are nouns.

Word	Noun	Adjective	Verb	Adverb
replenishment	Yes	No	No	No
refilling	Yes	No	No	No

As nouns, replenishment and refilling are synonyms defined as:

replenishment and refilling: filling again by supplying what has been used up

Other synonyms of replenishment include renewal, replacement.

replenishment (noun)	refilling (noun)
filling again by supplying what has been used up	filling again by supplying what has been used up