western poppy vs Papaver californicum

western poppy and Papaver californicum both are nouns.

Word	Noun	Adjective	Verb	Adverb
western poppy	Yes	No	No	No
Papaver californicum	Yes	No	No	No

As nouns, western poppy and Papaver californicum are synonyms defined as:

western poppy and Papaver californicum: showy annual of California with red flowers

western poppy (noun)	Papaver californicum (noun)
showy annual of California with red flowers	showy annual of California with red flowers