ecstasy vs cloud nine

ecstasy and cloud nine both are nouns.

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

As nouns, cloud nine is a hypernym of ecstasy; that is, cloud nine is a word with a broader meaning than ecstasy:

Other hypernyms of ecstasy include bliss, blissfulness, seventh heaven, walking on air.

ecstasy (noun)	cloud nine (noun)
street names for methylenedioxymethamphetamine	a state of extreme happiness
a state of being carried away by overwhelming emotion
a state of elated bliss