yellowish green vs yellow green

yellowish green and yellow green both are nouns.

Word	Noun	Adjective	Verb	Adverb
yellowish green	Yes	No	No	No
yellow green	Yes	No	No	No

As nouns, yellowish green and yellow green are synonyms defined as:

Other synonyms of yellowish green include chartreuse, Paris green, pea green.

yellowish green (noun)	yellow green (noun)
a shade of green tinged with yellow	a shade of green tinged with yellow