inkiness vs soot black

inkiness and soot black both are nouns.

Word	Noun	Adjective	Verb	Adverb
inkiness	Yes	No	No	No
soot black	Yes	No	No	No

As nouns, soot black is a hyponym of inkiness; that is, soot black is a word with a more specific, narrower meaning than inkiness:

inkiness: the quality or state of the achromatic color of least lightness (bearing the least resemblance to white)
soot black: a very dark black

Other hyponyms of inkiness include coal black, ebony, jet black, pitch black, sable.

inkiness (noun)	soot black (noun)
the quality or state of the achromatic color of least lightness (bearing the least resemblance to white)	a very dark black