canary yellow vs yellowness

canary yellow and yellowness both are nouns.

Word	Noun	Adjective	Verb	Adverb
canary yellow	Yes	No	No	No
yellowness	Yes	No	No	No

As nouns, yellowness is a hypernym of canary yellow; that is, yellowness is a word with a broader meaning than canary yellow:

canary yellow: a moderate yellow with a greenish tinge
yellowness: yellow color or pigment; the chromatic color resembling the hue of sunflowers or ripe lemons

Other hypernyms of canary yellow include yellow.

canary yellow (noun)	yellowness (noun)
a moderate yellow with a greenish tinge	yellow color or pigment; the chromatic color resembling the hue of sunflowers or ripe lemons