buckeroo vs cowherd

buckeroo and cowherd both are nouns.

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

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

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

Other hypernyms of buckeroo include cowhand, cowpoke, cowpuncher, puncher.

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