water mill vs milling machinery

water mill and milling machinery both are nouns.

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

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

water mill: a mill powered by a water wheel
milling machinery: machinery that processes materials by grinding or crushing

Other hypernyms of water mill include grinder, mill.

water mill (noun)	milling machinery (noun)
a mill powered by a water wheel	machinery that processes materials by grinding or crushing