bladder vs gallbladder

bladder and gallbladder both are nouns.

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

As nouns, gallbladder is a hyponym of bladder; that is, gallbladder is a word with a more specific, narrower meaning than bladder:

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

Other hyponyms of bladder include gall bladder, urinary bladder.

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