breathing in vs respiration

breathing in and respiration both are nouns.

Word	Noun	Adjective	Verb	Adverb
breathing in	Yes	No	No	No
respiration	Yes	No	No	No

breathing in (noun)	respiration (noun)
the act of inhaling; the drawing in of air (or other gases) as in breathing	the metabolic processes whereby certain organisms obtain energy from organic molecules; processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced and absorbed by the blood to be transported to the lungs
	the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation
	a single complete act of breathing in and out