whizbang vs banger

whizbang and banger both are nouns.

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

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

whizbang: a firecracker that (like the whizbang shell) makes a whizzing sound followed by a loud explosion
banger: firework consisting of a small explosive charge and fuse in a heavy paper casing

Other hypernyms of whizbang include cracker, firecracker.

whizbang (noun)	banger (noun)
a firecracker that (like the whizbang shell) makes a whizzing sound followed by a loud explosion	firework consisting of a small explosive charge and fuse in a heavy paper casing
a small high-velocity shell; it makes a whizzing sound followed by a bang when it hits	(British informal) pork sausage