megahertz vs MHz

megahertz and MHz both are nouns.

Word	Noun	Adjective	Verb	Adverb
megahertz	Yes	No	No	No
MHz	Yes	No	No	No

As nouns, megahertz and MHz are synonyms defined as:

Other synonyms of megahertz include Mc, megacycle, megacycle per second.

megahertz (noun)	MHz (noun)
one million periods per second	one million periods per second