Pisum sativum vs pea

Pisum sativum and pea both are nouns.

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

As nouns, pea is a hypernym of Pisum sativum; that is, pea is a word with a broader meaning than Pisum sativum:

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

Other hypernyms of Pisum sativum include pea plant.

Pisum sativum (noun)	pea (noun)
plant producing peas usually eaten fresh rather than dried	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
	the fruit or seed of a pea plant