megabit vs Mbit

megabit and Mbit both are nouns.

Word	Noun	Adjective	Verb	Adverb
megabit	Yes	No	No	No
Mbit	Yes	No	No	No

As nouns, megabit and Mbit are synonyms defined as:

megabit and Mbit: a unit of information equal to 1000 kilobits or 10^6 (1,000,000) bits

Other synonyms of megabit include Mb.

megabit (noun)	Mbit (noun)
a unit of information equal to 1000 kilobits or 10^6 (1,000,000) bits	a unit of information equal to 1000 kilobits or 10^6 (1,000,000) bits