emission vs effluvium

emission and effluvium both are nouns.

Word	Noun	Adjective	Verb	Adverb
emission	Yes	No	No	No
effluvium	Yes	No	No	No

As nouns, effluvium is a hyponym of emission; that is, effluvium is a word with a more specific, narrower meaning than emission:

Other hyponyms of emission include exudate, exudation, transudate, transudation, rheum, vaginal discharge.

emission (noun)	effluvium (noun)
the act of emitting; causing to flow forth	a foul-smelling outflow or vapor (especially a gaseous waste)
the occurrence of a flow of water (as from a pipe)
the release of electrons from parent atoms
any of several bodily processes by which substances go out of the body
a substance that is emitted or released