fill vs modify

fill is a noun but modify is not a noun.

Word	Noun	Adjective	Verb	Adverb
fill	Yes	No	Yes	No
modify	No	No	Yes	No

As verbs, modify is a hypernym of fill; that is, modify is a word with a broader meaning than fill:

Other hypernyms of fill include alter, change.

fill (noun)	modify (noun)
a quantity sufficient to satisfy
any material that fills a space or container

fill (verb)	modify (verb)
become full	make less severe or harsh or extreme
make full, also in a metaphorical sense	add a modifier to a constituent
plug with a substance	cause to change; make different; cause a transformation
fill to satisfaction
eat until one is sated
fill, satisfy or meet a want or need or condition or restriction
assume, as of positions or roles
appoint someone to (a position or a job)
occupy the whole of