Coreopsis gigantea vs giant coreopsis

Coreopsis gigantea and giant coreopsis both are nouns.

Word	Noun	Adjective	Verb	Adverb
Coreopsis gigantea	Yes	No	No	No
giant coreopsis	Yes	No	No	No

As nouns, Coreopsis gigantea and giant coreopsis are synonyms defined as:

Coreopsis gigantea and giant coreopsis: large treelike shrub having feathery leaves and clusters of large yellow flower heads; coastal southern California

Coreopsis gigantea (noun)	giant coreopsis (noun)
large treelike shrub having feathery leaves and clusters of large yellow flower heads; coastal southern California	large treelike shrub having feathery leaves and clusters of large yellow flower heads; coastal southern California