marsh milkweed vs Eupatorium purpureum

marsh milkweed and Eupatorium purpureum both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh milkweed	Yes	No	No	No
Eupatorium purpureum	Yes	No	No	No

As nouns, marsh milkweed and Eupatorium purpureum are synonyms defined as:

marsh milkweed and Eupatorium purpureum: North American herb having whorled leaves and terminal clusters of flowers spotted with purple

Other synonyms of marsh milkweed include Joe-Pye weed, purple boneset, trumpet weed.

marsh milkweed (noun)	Eupatorium purpureum (noun)
North American herb having whorled leaves and terminal clusters of flowers spotted with purple	North American herb having whorled leaves and terminal clusters of flowers spotted with purple