Campanula medium vs bellflower

Campanula medium and bellflower both are nouns.

Word	Noun	Adjective	Verb	Adverb
Campanula medium	Yes	No	No	No
bellflower	Yes	No	No	No

As nouns, bellflower is a hypernym of Campanula medium; that is, bellflower is a word with a broader meaning than Campanula medium:

Campanula medium: European biennial widely cultivated for its blue or violet or white flowers
bellflower: any of various plants of the genus Campanula having blue or white bell-shaped flowers

Other hypernyms of Campanula medium include campanula.

Campanula medium (noun)	bellflower (noun)
European biennial widely cultivated for its blue or violet or white flowers	any of various plants of the genus Campanula having blue or white bell-shaped flowers