Lathyrus palustris vs wild pea

Lathyrus palustris and wild pea both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lathyrus palustris	Yes	No	No	No
wild pea	Yes	No	No	No

As nouns, wild pea is a hypernym of Lathyrus palustris; that is, wild pea is a word with a broader meaning than Lathyrus palustris:

Lathyrus palustris: scrambling perennial of damp or marshy areas of Eurasia and North America with purplish flowers
wild pea: any of various plants of the family Leguminosae that usually grow like vines

Lathyrus palustris (noun)	wild pea (noun)
scrambling perennial of damp or marshy areas of Eurasia and North America with purplish flowers	any of various plants of the family Leguminosae that usually grow like vines