Gb vs Gbit

Gb and Gbit both are nouns.

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

As nouns, Gb and Gbit are synonyms defined as:

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

Other synonyms of Gb include gigabit.

Gb (noun)	Gbit (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