sunflower vs helianthus

sunflower and helianthus both are nouns.

Word	Noun	Adjective	Verb	Adverb
sunflower	Yes	No	No	No
helianthus	Yes	No	No	No

As nouns, sunflower and helianthus are synonyms defined as:

sunflower and helianthus: any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays

sunflower (noun)	helianthus (noun)
any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays	any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays