number crunching vs computing

number crunching and computing both are nouns.

Word	Noun	Adjective	Verb	Adverb
number crunching	Yes	No	No	No
computing	Yes	No	No	No

As nouns, computing is a hypernym of number crunching; that is, computing is a word with a broader meaning than number crunching:

number crunching: performing complex and lengthy numerical calculations
computing: the procedure of calculating; determining something by mathematical or logical methods

Other hypernyms of number crunching include calculation, computation.

number crunching (noun)	computing (noun)
performing complex and lengthy numerical calculations	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