peacock blue vs greenish blue

peacock blue and greenish blue both are nouns.

Word	Noun	Adjective	Verb	Adverb
peacock blue	Yes	No	No	No
greenish blue	Yes	No	No	No

As nouns, peacock blue and greenish blue are synonyms defined as:

Other synonyms of peacock blue include aqua, aquamarine, cobalt blue, turquoise.

peacock blue (noun)	greenish blue (noun)
a shade of blue tinged with green	a shade of blue tinged with green