elation vs cloud nine

elation and cloud nine both are nouns.

Word	Noun	Adjective	Verb	Adverb
elation	Yes	No	No	No
cloud nine	Yes	No	No	No

As nouns, cloud nine is a hyponym of elation; that is, cloud nine is a word with a more specific, narrower meaning than elation:

elation: an exhilarating psychological state of pride and optimism; an absence of depression
cloud nine: a state of extreme happiness

Other hyponyms of elation include bliss, blissfulness, seventh heaven, walking on air, high, high.

elation (noun)	cloud nine (noun)
a feeling of joy and pride	a state of extreme happiness
an exhilarating psychological state of pride and optimism; an absence of depression