rarity vs curio

rarity and curio both are nouns.

Word	Noun	Adjective	Verb	Adverb
rarity	Yes	No	No	No
curio	Yes	No	No	No

As nouns, rarity and curio are synonyms defined as:

Other synonyms of rarity include curiosity, oddity, oddment, peculiarity.

rarity (noun)	curio (noun)
something unusual -- perhaps worthy of collecting	something unusual -- perhaps worthy of collecting
a rarified quality
noteworthy scarcity