sheepman vs herder

sheepman and herder both are nouns.

Word	Noun	Adjective	Verb	Adverb
sheepman	Yes	No	No	No
herder	Yes	No	No	No

As nouns, herder is a hypernym of sheepman; that is, herder is a word with a broader meaning than sheepman:

sheepman: a herder of sheep (on an open range); someone who keeps the sheep together in a flock
herder: someone who drives a herd

Other hypernyms of sheepman include drover, herdsman.

sheepman (noun)	herder (noun)
a man who raises (or tends) sheep	someone who drives a herd
a herder of sheep (on an open range); someone who keeps the sheep together in a flock