milling machinery vs machinery

milling machinery and machinery both are nouns.

Word	Noun	Adjective	Verb	Adverb
milling machinery	Yes	No	No	No
machinery	Yes	No	No	No

As nouns, machinery is a hypernym of milling machinery; that is, machinery is a word with a broader meaning than milling machinery:

milling machinery: machinery that processes materials by grinding or crushing
machinery: machines or machine systems collectively

milling machinery (noun)	machinery (noun)
machinery that processes materials by grinding or crushing	machines or machine systems collectively
	a system of means and activities whereby a social institution functions