Arbutus unedo vs arbutus

Arbutus unedo and arbutus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Arbutus unedo	Yes	No	No	No
arbutus	Yes	No	No	No

As nouns, arbutus is a hypernym of Arbutus unedo; that is, arbutus is a word with a broader meaning than Arbutus unedo:

Arbutus unedo: small evergreen European shrubby tree bearing many-seeded scarlet berries that are edible but bland; of Ireland, southern Europe, Asia Minor
arbutus: any of several evergreen shrubs of the genus Arbutus of temperate Europe and America

Arbutus unedo (noun)	arbutus (noun)
small evergreen European shrubby tree bearing many-seeded scarlet berries that are edible but bland; of Ireland, southern Europe, Asia Minor	any of several evergreen shrubs of the genus Arbutus of temperate Europe and America