pea green vs yellowish green

pea green and yellowish green both are nouns.

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

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

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

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