pea vs Pisum sativum

pea and Pisum sativum both are nouns.

Word	Noun	Adjective	Verb	Adverb
pea	Yes	No	No	No
Pisum sativum	Yes	No	No	No

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

pea: a leguminous plant of the genus Pisum with small white flowers and long green pods containing edible green seeds
Pisum sativum: plant producing peas usually eaten fresh rather than dried

pea (noun)	Pisum sativum (noun)
seed of a pea plant used for food	plant producing peas usually eaten fresh rather than dried
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