clover-leaf roll vs bun

clover-leaf roll and bun both are nouns.

Word	Noun	Adjective	Verb	Adverb
clover-leaf roll	Yes	No	No	No
bun	Yes	No	No	No

As nouns, bun is a hypernym of clover-leaf roll; that is, bun is a word with a broader meaning than clover-leaf roll:

clover-leaf roll: yeast-raised dinner roll made by baking three small balls of dough in each cup of a muffin pan
bun: small rounded bread either plain or sweet

Other hypernyms of clover-leaf roll include roll.

clover-leaf roll (noun)	bun (noun)
yeast-raised dinner roll made by baking three small balls of dough in each cup of a muffin pan	small rounded bread either plain or sweet