purple locoweed vs crazy weed

purple locoweed and crazy weed both are nouns.

Word	Noun	Adjective	Verb	Adverb
purple locoweed	Yes	No	No	No
crazy weed	Yes	No	No	No

As nouns, crazy weed is a hypernym of purple locoweed; that is, crazy weed is a word with a broader meaning than purple locoweed:

purple locoweed: tufted locoweed of southwestern United States having purple or pink to white flowers
crazy weed: any of several leguminous plants of western North America causing locoism in livestock

Other hypernyms of purple locoweed include crazyweed, locoweed.

purple locoweed (noun)	crazy weed (noun)
tufted locoweed of southwestern United States having purple or pink to white flowers	any of several leguminous plants of western North America causing locoism in livestock