wacko vs oddball

wacko and oddball both are nouns.

Word	Noun	Adjective	Verb	Adverb
wacko	Yes	No	No	No
oddball	Yes	No	No	No

As nouns, oddball is a hypernym of wacko; that is, oddball is a word with a broader meaning than wacko:

Other hypernyms of wacko include eccentric, eccentric person, flake, geek.

wacko (noun)	oddball (noun)
a person who is regarded as eccentric or mad	a person with an unusual or odd personality