hertz vs Hz

hertz and Hz both are nouns.

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

As nouns, hertz and Hz are synonyms defined as:

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

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

hertz (noun)	Hz (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)