high blood pressure vs hypertension

high blood pressure and hypertension both are nouns.

Word	Noun	Adjective	Verb	Adverb
high blood pressure	Yes	No	No	No
hypertension	Yes	No	No	No

As nouns, high blood pressure and hypertension are synonyms defined as:

high blood pressure and hypertension: a common disorder in which blood pressure remains abnormally high (a reading of 140/90 mm Hg or greater)

high blood pressure (noun)	hypertension (noun)
a common disorder in which blood pressure remains abnormally high (a reading of 140/90 mm Hg or greater)	a common disorder in which blood pressure remains abnormally high (a reading of 140/90 mm Hg or greater)