replacement vs refilling

replacement and refilling both are nouns.

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

As nouns, replacement and refilling are synonyms defined as:

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

Other synonyms of replacement include renewal, replenishment.

replacement (noun)	refilling (noun)
the act of furnishing an equivalent person or thing in the place of another	filling again by supplying what has been used up
a person or thing that takes or can take the place of another
an event in which one thing is substituted for another
a person who follows next in order
someone who takes the place of another person
filling again by supplying what has been used up