cowpuncher vs buckaroo

cowpuncher and buckaroo both are nouns.

Word	Noun	Adjective	Verb	Adverb
cowpuncher	Yes	No	No	No
buckaroo	Yes	No	No	No

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

cowpuncher: a hired hand who tends cattle and performs other duties on horseback
buckaroo: local names for a cowboy (`vaquero' is used especially in southwestern and central Texas and `buckaroo' is used especially in California)

Other hyponyms of cowpuncher include buckeroo, vaquero, cowgirl, gaucho, horse wrangler, wrangler, roper, cattleman, cowboy, cowman.

cowpuncher (noun)	buckaroo (noun)
a hired hand who tends cattle and performs other duties on horseback	local names for a cowboy (`vaquero' is used especially in southwestern and central Texas and `buckaroo' is used especially in California)