Erica carnea vs erica

Erica carnea and erica both are nouns.

Word	Noun	Adjective	Verb	Adverb
Erica carnea	Yes	No	No	No
erica	Yes	No	No	No

As nouns, erica is a hypernym of Erica carnea; that is, erica is a word with a broader meaning than Erica carnea:

Erica carnea: dwarf European shrub with very early blooming bell-shaped red flowers
erica: any plant of the genus Erica

Other hypernyms of Erica carnea include true heath.

Erica carnea (noun)	erica (noun)
dwarf European shrub with very early blooming bell-shaped red flowers	any plant of the genus Erica