stockman vs cattleman

stockman and cattleman both are nouns.

Word	Noun	Adjective	Verb	Adverb
stockman	Yes	No	No	No
cattleman	Yes	No	No	No

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

Other hyponyms of stockman include breeder, stock breeder, beef man, cow man, sheepman.

stockman (noun)	cattleman (noun)
farmer who breed or raises livestock	a man who raises (or tends) cattle
	a male hired hand who tends cattle and performs other duties on horseback