common lettuce vs garden lettuce

common lettuce and garden lettuce both are nouns.

Word	Noun	Adjective	Verb	Adverb
common lettuce	Yes	No	No	No
garden lettuce	Yes	No	No	No

As nouns, common lettuce and garden lettuce are synonyms defined as:

common lettuce and garden lettuce: annual or perennial garden plant having succulent leaves used in salads; widely grown

Other synonyms of common lettuce include Lactuca sativa.

common lettuce (noun)	garden lettuce (noun)
annual or perennial garden plant having succulent leaves used in salads; widely grown	annual or perennial garden plant having succulent leaves used in salads; widely grown