gigacycle per second vs GHz

gigacycle per second and GHz both are nouns.

Word	Noun	Adjective	Verb	Adverb
gigacycle per second	Yes	No	No	No
GHz	Yes	No	No	No

As nouns, gigacycle per second and GHz are synonyms defined as:

Other synonyms of gigacycle per second include Gc, gigacycle, gigahertz.

gigacycle per second (noun)	GHz (noun)
1,000,000,000 periods per second	1,000,000,000 periods per second