overspill vs overflow

overspill and overflow both are nouns.

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

As nouns, overspill and overflow are synonyms defined as:

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

Other synonyms of overspill include runoff.

overspill (noun)	overflow (noun)
the occurrence of surplus liquid (as water) exceeding the limit or capacity	a large flow
the relocation of people from overcrowded cities; they are accommodated in new houses or apartments in smaller towns	the occurrence of surplus liquid (as water) exceeding the limit or capacity

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