round out vs modify

round out and modify both are verbs.

Word	Noun	Adjective	Verb	Adverb
round out	No	No	Yes	No
modify	No	No	Yes	No

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

Other hypernyms of round out include alter, change.

round out (verb)	modify (verb)
make bigger or better or more complete	make less severe or harsh or extreme
make round	add a modifier to a constituent
express as a round number	cause to change; make different; cause a transformation
fill out