refilling vs filling

refilling and filling both are nouns.

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

As nouns, filling is a hypernym of refilling; that is, filling is a word with a broader meaning than refilling:

refilling (noun)	filling (noun)
filling again by supplying what has been used up	the act of filling something
	the yarn woven across the warp yarn in weaving
	(dentistry) a dental appliance consisting of any of various substances (as metal or plastic) inserted into a prepared cavity in a tooth
	a food mixture used to fill pastry or sandwiches etc.
	flow into something (as a container)
	any material that fills a space or container