pampas grass vs Cortaderia selloana

pampas grass and Cortaderia selloana both are nouns.

Word	Noun	Adjective	Verb	Adverb
pampas grass	Yes	No	No	No
Cortaderia selloana	Yes	No	No	No

As nouns, pampas grass and Cortaderia selloana are synonyms defined as:

pampas grass and Cortaderia selloana: tall perennial grass of Pampas of South America having silvery plumes and growing in large dense clumps

pampas grass (noun)	Cortaderia selloana (noun)
tall perennial grass of Pampas of South America having silvery plumes and growing in large dense clumps	tall perennial grass of Pampas of South America having silvery plumes and growing in large dense clumps