mainframe vs central processing unit

mainframe and central processing unit both are nouns.

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

As nouns, mainframe and central processing unit are synonyms defined as:

mainframe and central processing unit: (computer science) the part of a computer (a microprocessor chip) that does most of the data processing

Other synonyms of mainframe include C.P.U., central processor, CPU, processor.

mainframe (noun)	central processing unit (noun)
(computer science) the part of a computer (a microprocessor chip) that does most of the data processing	(computer science) the part of a computer (a microprocessor chip) that does most of the data processing
a large digital computer serving 100-400 users and occupying a special air-conditioned room