herder vs sheepman

herder and sheepman both are nouns.

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

As nouns, sheepman is a hyponym of herder; that is, sheepman is a word with a more specific, narrower meaning than herder:

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

Other hyponyms of herder include goat herder, goatherd, sheepherder, shepherd, pigman, swineherd.

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