bliss vs cloud nine

bliss and cloud nine both are nouns.

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

As nouns, bliss and cloud nine are synonyms defined as:

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

bliss (noun)	cloud nine (noun)
a state of extreme happiness	a state of extreme happiness