clover vs trefoil

clover and trefoil both are nouns.

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

As nouns, clover and trefoil are synonyms defined as:

clover (noun)	trefoil (noun)
a plant of the genus Trifolium	an architectural ornament in the form of three arcs arranged in a circle
	a plant of the genus Trifolium
	any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves