collectable vs oddity

collectable and oddity both are nouns.

Word	Noun	Adjective	Verb	Adverb
collectable	Yes	Yes	No	No
oddity	Yes	No	No	No

As nouns, oddity is a hypernym of collectable; that is, oddity is a word with a broader meaning than collectable:

collectable: things considered to be worth collecting (not necessarily valuable or antique)
oddity: something unusual -- perhaps worthy of collecting

Other hypernyms of collectable include curio, curiosity, oddment, peculiarity, rarity.

collectable (noun)	oddity (noun)
things considered to be worth collecting (not necessarily valuable or antique)	something unusual -- perhaps worthy of collecting
	a strange attitude or habit
	eccentricity that is not easily explained

collectable (adjective)	oddity (adjective)
subject to or requiring payment especially as specified