American holly vs holly

American holly and holly both are nouns.

Word	Noun	Adjective	Verb	Adverb
American holly	Yes	No	No	No
holly	Yes	No	No	No

As nouns, holly is a hypernym of American holly; that is, holly is a word with a broader meaning than American holly:

American holly: an evergreen tree (Ilex opaca)
holly: any tree or shrub of the genus Ilex having red berries and shiny evergreen leaves with prickly edges

Other hypernyms of American holly include poisonous plant.

American holly (noun)	holly (noun)
an evergreen tree (Ilex opaca)	any tree or shrub of the genus Ilex having red berries and shiny evergreen leaves with prickly edges