bun vs staff of life

bun and staff of life both are nouns.

Word	Noun	Adjective	Verb	Adverb
bun	Yes	No	No	No
staff of life	Yes	No	No	No

As nouns, staff of life is a hypernym of bun; that is, staff of life is a word with a broader meaning than bun:

bun: small rounded bread either plain or sweet
staff of life: food made from dough of flour or meal and usually raised with yeast or baking powder and then baked

Other hypernyms of bun include bread, breadstuff.

bun (noun)	staff of life (noun)
small rounded bread either plain or sweet	food made from dough of flour or meal and usually raised with yeast or baking powder and then baked