blissfulness vs cloud nine

blissfulness and cloud nine both are nouns.

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

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

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

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