electronic mail vs computing

electronic mail and computing both are nouns.

Word	Noun	Adjective	Verb	Adverb
electronic mail	Yes	No	No	No
computing	Yes	No	No	No

electronic mail (noun)	computing (noun)
(computer science) a system of world-wide electronic communication in which a computer user can compose a message at one terminal that can be regenerated at the recipient's terminal when the recipient logs in	the procedure of calculating; determining something by mathematical or logical methods
	the branch of engineering science that studies (with the aid of computers) computable processes and structures