Lactuca sativa capitata vs head lettuce

Lactuca sativa capitata and head lettuce both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lactuca sativa capitata	Yes	No	No	No
head lettuce	Yes	No	No	No

As nouns, Lactuca sativa capitata and head lettuce are synonyms defined as:

Lactuca sativa capitata and head lettuce: distinguished by leaves arranged in a dense rosette that develop into a compact ball

Lactuca sativa capitata (noun)	head lettuce (noun)
distinguished by leaves arranged in a dense rosette that develop into a compact ball	distinguished by leaves arranged in a dense rosette that develop into a compact ball