yellow trefoil vs medick

yellow trefoil and medick both are nouns.

Word	Noun	Adjective	Verb	Adverb
yellow trefoil	Yes	No	No	No
medick	Yes	No	No	No

As nouns, medick is a hypernym of yellow trefoil; that is, medick is a word with a broader meaning than yellow trefoil:

yellow trefoil: prostrate European herb with small yellow flowers and curved black pods; naturalized in North America
medick: any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves

Other hypernyms of yellow trefoil include medic, trefoil.

yellow trefoil (noun)	medick (noun)
prostrate European herb with small yellow flowers and curved black pods; naturalized in North America	any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves