Lactuca vs Lactuca sativa

Lactuca and Lactuca sativa both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lactuca	Yes	No	No	No
Lactuca sativa	Yes	No	No	No

Lactuca (noun)	Lactuca sativa (noun)
an herb with milky juice: lettuce; prickly lettuce	annual or perennial garden plant having succulent leaves used in salads; widely grown