dairy cattle vs milch cow

dairy cattle and milch cow both are nouns.

Word	Noun	Adjective	Verb	Adverb
dairy cattle	Yes	No	No	No
milch cow	Yes	No	No	No

As nouns, dairy cattle and milch cow are synonyms defined as:

Other synonyms of dairy cattle include dairy cow, milcher, milk cow, milker.

dairy cattle (noun)	milch cow (noun)
cattle that are reared for their milk	cattle that are reared for their milk