cowman vs cowherd

cowman and cowherd both are nouns.

Word	Noun	Adjective	Verb	Adverb
cowman	Yes	No	No	No
cowherd	Yes	No	No	No

As nouns, cowherd is a hypernym of cowman; that is, cowherd is a word with a broader meaning than cowman:

cowman: a male hired hand who tends cattle and performs other duties on horseback
cowherd: a hired hand who tends cattle and performs other duties on horseback

Other hypernyms of cowman include cowhand, cowpoke, cowpuncher, puncher, adult male, man.

cowman (noun)	cowherd (noun)
a male hired hand who tends cattle and performs other duties on horseback	a hired hand who tends cattle and performs other duties on horseback