pea vs pea plant

pea and pea plant both are nouns.

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

As nouns, pea and pea plant are synonyms defined as:

pea and pea plant: a leguminous plant of the genus Pisum with small white flowers and long green pods containing edible green seeds

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