pea vs green pea

pea and green pea both are nouns.

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

As nouns, green pea is a hyponym of pea; that is, green pea is a word with a more specific, narrower meaning than pea:

Other hyponyms of pea include garden pea, marrowfat pea, cajan pea, dahl, pigeon pea, field pea.

pea (noun)	green pea (noun)
seed of a pea plant used for food	fresh pea
a leguminous plant of the genus Pisum with small white flowers and long green pods containing edible green seeds
the fruit or seed of a pea plant