Mb vs kb

Mb and kb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mb	Yes	No	No	No
kb	Yes	No	No	No

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