milch cow vs milker

milch cow and milker both are nouns.

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

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

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

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