leaf lettuce vs leaf lettuce

leaf lettuce and leaf lettuce both are nouns.

Word	Noun	Adjective	Verb	Adverb
leaf lettuce	Yes	No	No	No
leaf lettuce	Yes	No	No	No

leaf lettuce (noun)	leaf lettuce (noun)
lettuce with loosely curled leaves that do not form a compact head	lettuce with loosely curled leaves that do not form a compact head
distinguished by leaves having curled or incised leaves forming a loose rosette that does not develop into a compact head	distinguished by leaves having curled or incised leaves forming a loose rosette that does not develop into a compact head