perennial ragweed vs western ragweed

perennial ragweed and western ragweed both are nouns.

Word	Noun	Adjective	Verb	Adverb
perennial ragweed	Yes	No	No	No
western ragweed	Yes	No	No	No

As nouns, perennial ragweed and western ragweed are synonyms defined as:

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

Other synonyms of perennial ragweed include Ambrosia psilostachya.

perennial ragweed (noun)	western ragweed (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