bialystoker vs onion roll

bialystoker and onion roll both are nouns.

Word	Noun	Adjective	Verb	Adverb
bialystoker	Yes	No	No	No
onion roll	Yes	No	No	No

As nouns, onion roll is a hypernym of bialystoker; that is, onion roll is a word with a broader meaning than bialystoker:

bialystoker (noun)	onion roll (noun)
flat crusty-bottomed onion roll	yeast-raised roll flavored with onion