roper vs cowpoke

roper and cowpoke both are nouns.

Word	Noun	Adjective	Verb	Adverb
roper	Yes	No	No	No
cowpoke	Yes	No	No	No

As nouns, cowpoke is a hypernym of roper; that is, cowpoke is a word with a broader meaning than roper:

roper: a cowboy who uses a lasso to rope cattle or horses
cowpoke: a hired hand who tends cattle and performs other duties on horseback

Other hypernyms of roper include cowhand, cowherd, cowpuncher, puncher.

roper (noun)	cowpoke (noun)
a craftsman who makes ropes	a hired hand who tends cattle and performs other duties on horseback
a cowboy who uses a lasso to rope cattle or horses
a decoy who lures customers into a gambling establishment (especially one with a fixed game)