jet-black vs coal-black

jet-black and coal-black both are adjectives.

Word	Noun	Adjective	Verb	Adverb
jet-black	No	Yes	No	No
coal-black	No	Yes	No	No

As adjectives, jet-black and coal-black are synonyms defined as:

jet-black and coal-black: of the blackest black; similar to the color of jet or coal

Other synonyms of jet-black include jet, pitchy, sooty.

jet-black (adjective)	coal-black (adjective)
of the blackest black; similar to the color of jet or coal	of the blackest black; similar to the color of jet or coal