dark-green vs greenish

dark-green and greenish both are adjectives.

Word	Noun	Adjective	Verb	Adverb
dark-green	No	Yes	No	No
greenish	No	Yes	No	No

As adjectives, dark-green and greenish are synonyms defined as:

dark-green and greenish: of the color between blue and yellow in the color spectrum; similar to the color of fresh grass

Other synonyms of dark-green include green, light-green.

dark-green (adjective)	greenish (adjective)
of the color between blue and yellow in the color spectrum; similar to the color of fresh grass	of the color between blue and yellow in the color spectrum; similar to the color of fresh grass