western ragweed vs Ambrosia psilostachya

western ragweed and Ambrosia psilostachya both are nouns.

Word	Noun	Adjective	Verb	Adverb
western ragweed	Yes	No	No	No
Ambrosia psilostachya	Yes	No	No	No

As nouns, western ragweed and Ambrosia psilostachya are synonyms defined as:

western ragweed and Ambrosia psilostachya: coarse perennial ragweed with creeping roots of dry barren lands of southwestern United States and Mexico

Other synonyms of western ragweed include perennial ragweed.

western ragweed (noun)	Ambrosia psilostachya (noun)
coarse perennial ragweed with creeping roots of dry barren lands of southwestern United States and Mexico	coarse perennial ragweed with creeping roots of dry barren lands of southwestern United States and Mexico