runoff vs overflow

runoff and overflow both are nouns.

Word	Noun	Adjective	Verb	Adverb
runoff	Yes	No	No	No
overflow	Yes	No	Yes	No

As nouns, runoff and overflow are synonyms defined as:

runoff and overflow: the occurrence of surplus liquid (as water) exceeding the limit or capacity

Other synonyms of runoff include overspill.

runoff (noun)	overflow (noun)
a final election to resolve an earlier election that did not produce a winner	a large flow
the occurrence of surplus liquid (as water) exceeding the limit or capacity	the occurrence of surplus liquid (as water) exceeding the limit or capacity

runoff (verb)	overflow (verb)
	overflow with a certain feeling
	flow or run over (a limit or brim)