trefoil vs clover

trefoil and clover both are nouns.

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

As nouns, trefoil and clover are synonyms defined as:

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