banger vs firework

banger and firework both are nouns.

Word	Noun	Adjective	Verb	Adverb
banger	Yes	No	No	No
firework	Yes	No	No	No

As nouns, firework is a hypernym of banger; that is, firework is a word with a broader meaning than banger:

banger: firework consisting of a small explosive charge and fuse in a heavy paper casing
firework: (usually plural) a device with an explosive that burns at a low rate and with colored flames; can be used to illuminate areas or send signals etc.

Other hypernyms of banger include pyrotechnic.

banger (noun)	firework (noun)
firework consisting of a small explosive charge and fuse in a heavy paper casing	(usually plural) a device with an explosive that burns at a low rate and with colored flames; can be used to illuminate areas or send signals etc.
(British informal) pork sausage