dairy cow vs milch cow

dairy cow and milch cow both are nouns.

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

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

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

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