dairy farmer vs dairyman

dairy farmer and dairyman both are nouns.

Word	Noun	Adjective	Verb	Adverb
dairy farmer	Yes	No	No	No
dairyman	Yes	No	No	No

As nouns, dairy farmer and dairyman are synonyms defined as:

dairy farmer (noun)	dairyman (noun)
the owner or manager of a dairy	the owner or manager of a dairy
	a man who works in a dairy