fill out vs round out

fill out and round out both are verbs.

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

As verbs, fill out and round out are synonyms defined as:

fill out (verb)	round out (verb)
become round, plump, or shapely	make bigger or better or more complete
make bigger or better or more complete	make round
write all the required information onto a form	express as a round number
make fat or plump	fill out
line or stuff with soft material
supplement what is thought to be deficient