Hz vs hertz

Hz and hertz both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hz	Yes	No	No	No
hertz	Yes	No	No	No

As nouns, Hz and hertz are synonyms defined as:

Hz and hertz: the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)

Other synonyms of Hz include cps, cycle, cycle per second, cycles/second.

Hz (noun)	hertz (noun)
the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)	the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)