cos lettuce vs Lactuca sativa longifolia

cos lettuce and Lactuca sativa longifolia both are nouns.

Word	Noun	Adjective	Verb	Adverb
cos lettuce	Yes	No	No	No
Lactuca sativa longifolia	Yes	No	No	No

As nouns, cos lettuce and Lactuca sativa longifolia are synonyms defined as:

cos lettuce and Lactuca sativa longifolia: lettuce with long dark-green spoon-shaped leaves

Other synonyms of cos lettuce include romaine lettuce.

cos lettuce (noun)	Lactuca sativa longifolia (noun)
lettuce with long dark-green leaves in a loosely packed elongated head	lettuce with long dark-green spoon-shaped leaves
lettuce with long dark-green spoon-shaped leaves