Camellia japonica vs camellia

Camellia japonica and camellia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Camellia japonica	Yes	No	No	No
camellia	Yes	No	No	No

As nouns, camellia is a hypernym of Camellia japonica; that is, camellia is a word with a broader meaning than Camellia japonica:

Camellia japonica: greenhouse shrub with glossy green leaves and showy fragrant rose-like flowers; cultivated in many varieties
camellia: any of several shrubs or small evergreen trees having solitary white or pink or reddish flowers

Other hypernyms of Camellia japonica include camelia.

Camellia japonica (noun)	camellia (noun)
greenhouse shrub with glossy green leaves and showy fragrant rose-like flowers; cultivated in many varieties	any of several shrubs or small evergreen trees having solitary white or pink or reddish flowers