butterweed vs wild flower

butterweed and wild flower both are nouns.

Word	Noun	Adjective	Verb	Adverb
butterweed	Yes	No	No	No
wild flower	Yes	No	No	No

As nouns, wild flower is a hypernym of butterweed; that is, wild flower is a word with a broader meaning than butterweed:

Other hypernyms of butterweed include wildflower.

butterweed (noun)	wild flower (noun)
any of several yellow-flowered plants of the genus Packera; often placed in genus Senecio	wild or uncultivated flowering plant
American ragwort with yellow flowers