omission vs exclusion

omission and exclusion both are nouns.

Word	Noun	Adjective	Verb	Adverb
omission	Yes	No	No	No
exclusion	Yes	No	No	No

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

Other hyponyms of omission include inadvertence, oversight, pretermission, elision, exception.

omission (noun)	exclusion (noun)
a mistake resulting from neglect	the act of forcing out someone or something
neglecting to do something; leaving out or passing over something	a deliberate act of omission
any process whereby sounds or words are left out of spoken words or phrases	the state of being excluded
something that has been omitted	the state of being excommunicated