central processing unit vs computer

central processing unit and computer both are nouns.

Word	Noun	Adjective	Verb	Adverb
central processing unit	Yes	No	No	No
computer	Yes	No	No	No

central processing unit (noun)	computer (noun)
(computer science) the part of a computer (a microprocessor chip) that does most of the data processing	a machine for performing calculations automatically
	an expert at calculation (or at operating calculating machines)