prickly pear vs nopal

prickly pear and nopal both are nouns.

Word	Noun	Adjective	Verb	Adverb
prickly pear	Yes	No	No	No
nopal	Yes	No	No	No

As nouns, nopal is a hyponym of prickly pear; that is, nopal is a word with a more specific, narrower meaning than prickly pear:

prickly pear: cacti having spiny flat joints and oval fruit that is edible in some species; often used as food for stock
nopal: cactus having yellow flowers and purple fruits

Other hyponyms of prickly pear include Opuntia lindheimeri, Opuntia tuna, tuna.

prickly pear (noun)	nopal (noun)
round or pear-shaped spiny fruit of any of various prickly pear cacti	any of several cacti of the genus Nopalea resembling prickly pears
cacti having spiny flat joints and oval fruit that is edible in some species; often used as food for stock	cactus having yellow flowers and purple fruits