candour vs honestness

candour and honestness both are nouns.

Word	Noun	Adjective	Verb	Adverb
candour	Yes	No	No	No
honestness	Yes	No	No	No

As nouns, honestness is a hypernym of candour; that is, honestness is a word with a broader meaning than candour:

candour: the quality of being honest and straightforward in attitude and speech
honestness: the quality of being honest

Other hypernyms of candour include honesty.

candour (noun)	honestness (noun)
the quality of being honest and straightforward in attitude and speech	the quality of being honest
ability to make judgments free from discrimination or dishonesty