light-green vs greenish

light-green and greenish both are adjectives.

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

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

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

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

light-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