Gb vs gigabit

Gb and gigabit both are nouns.

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

As nouns, Gb and gigabit are synonyms defined as:

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

Other synonyms of Gb include Gbit.

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