walking on air vs seventh heaven

walking on air and seventh heaven both are nouns.

Word	Noun	Adjective	Verb	Adverb
walking on air	Yes	No	No	No
seventh heaven	Yes	No	No	No

As nouns, walking on air and seventh heaven are synonyms defined as:

Other synonyms of walking on air include bliss, blissfulness, cloud nine.

walking on air (noun)	seventh heaven (noun)
a state of extreme happiness	a state of extreme happiness