pasta vs orzo

pasta and orzo both are nouns.

Word	Noun	Adjective	Verb	Adverb
pasta	Yes	No	No	No
orzo	Yes	No	No	No

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

pasta: shaped and dried dough made from flour and water and sometimes egg
orzo: pasta shaped like pearls of barley; frequently prepared with lamb in Greek cuisine

pasta (noun)	orzo (noun)
shaped and dried dough made from flour and water and sometimes egg	pasta shaped like pearls of barley; frequently prepared with lamb in Greek cuisine
a dish that contains pasta as its main ingredient