shortness of breath vs breathlessness

shortness of breath and breathlessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
shortness of breath	Yes	No	No	No
breathlessness	Yes	No	No	No

As nouns, shortness of breath and breathlessness are synonyms defined as:

Other synonyms of shortness of breath include SOB.

shortness of breath (noun)	breathlessness (noun)
a dyspneic condition	a dyspneic condition