bellflower vs herbaceous plant

bellflower and herbaceous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
bellflower	Yes	No	No	No
herbaceous plant	Yes	No	No	No

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

bellflower: any of various plants of the genus Campanula having blue or white bell-shaped flowers
herbaceous plant: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

Other hypernyms of bellflower include herb.

bellflower (noun)	herbaceous plant (noun)
any of various plants of the genus Campanula having blue or white bell-shaped flowers	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests