effusion vs overflow

effusion and overflow both are nouns.

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

As nouns, overflow is a hypernym of effusion; that is, overflow is a word with a broader meaning than effusion:

Other hypernyms of effusion include flood, outpouring.

effusion (noun)	overflow (noun)
flow under pressure	a large flow
an unrestrained expression of emotion	the occurrence of surplus liquid (as water) exceeding the limit or capacity

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