effusion vs outpouring

effusion and outpouring both are nouns.

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

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

Other hypernyms of effusion include flood, overflow.

effusion (noun)	outpouring (noun)
flow under pressure	a large flow
an unrestrained expression of emotion	the rapid and continuous delivery of linguistic communication (spoken or written)
	the pouring forth of a fluid
	a sudden rapid flow (as of water)
	a natural flow of ground water