purple clover vs clover

purple clover and clover both are nouns.

Word	Noun	Adjective	Verb	Adverb
purple clover	Yes	No	No	No
clover	Yes	No	No	No

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

purple clover: erect to decumbent short-lived perennial having red-purple to pink flowers; the most commonly grown forage clover
clover: a plant of the genus Trifolium

Other hypernyms of purple clover include trefoil.

purple clover (noun)	clover (noun)
erect to decumbent short-lived perennial having red-purple to pink flowers; the most commonly grown forage clover	a plant of the genus Trifolium