emission vs egression

emission and egression both are nouns.

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

As nouns, egression is a hypernym of emission; that is, egression is a word with a broader meaning than emission:

Other hypernyms of emission include egress, emergence.

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