egression vs emission

egression and emission both are nouns.

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

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

Other hyponyms of egression include surfacing, emanation.

egression (noun)	emission (noun)
the act of coming (or going) out; becoming apparent	the act of emitting; causing to flow forth
	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