gigabit vs Gb

gigabit and Gb both are nouns.

Word	Noun	Adjective	Verb	Adverb
gigabit	Yes	No	No	No
Gb	Yes	No	No	No

As nouns, gigabit and Gb are synonyms defined as:

gigabit and Gb: a unit of information equal to 1000 megabits or 10^9 (1,000,000,000) bits

Other synonyms of gigabit include Gbit.

gigabit (noun)	Gb (noun)
a unit of information equal to 1000 megabits or 10^9 (1,000,000,000) bits	a unit of magnetomotive force equal to 0.7958 ampere-turns
	a unit of information equal to 1000 megabits or 10^9 (1,000,000,000) bits