gallbladder vs bladder

gallbladder and bladder both are nouns.

Word	Noun	Adjective	Verb	Adverb
gallbladder	Yes	No	No	No
bladder	Yes	No	No	No

As nouns, bladder is a hypernym of gallbladder; that is, bladder is a word with a broader meaning than gallbladder:

gallbladder: a muscular sac attached to the liver that stores bile (secreted by the liver) until it is needed for digestion
bladder: a distensible membranous sac (usually containing liquid or gas)

Other hypernyms of gallbladder include vesica.

gallbladder (noun)	bladder (noun)
a muscular sac attached to the liver that stores bile (secreted by the liver) until it is needed for digestion	a bag that fills with air
	a distensible membranous sac (usually containing liquid or gas)