exhalation vs breathing out

exhalation and breathing out both are nouns.

Word	Noun	Adjective	Verb	Adverb
exhalation	Yes	No	No	No
breathing out	Yes	No	No	No

As nouns, exhalation and breathing out are synonyms defined as:

Other synonyms of exhalation include expiration.

exhalation (noun)	breathing out (noun)
the act of expelling air from the lungs	the act of expelling air from the lungs
exhaled breath