eclipsis vs omission

eclipsis and omission both are nouns.

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

As nouns, omission is a hypernym of eclipsis; that is, omission is a word with a broader meaning than eclipsis:

eclipsis: omission or suppression of parts of words or sentences
omission: any process whereby sounds or words are left out of spoken words or phrases

Other hypernyms of eclipsis include deletion.

eclipsis (noun)	omission (noun)
omission or suppression of parts of words or sentences	a mistake resulting from neglect
	neglecting to do something; leaving out or passing over something
	any process whereby sounds or words are left out of spoken words or phrases
	something that has been omitted