tall bellflower vs Campanula americana

tall bellflower and Campanula americana both are nouns.

Word	Noun	Adjective	Verb	Adverb
tall bellflower	Yes	No	No	No
Campanula americana	Yes	No	No	No

As nouns, tall bellflower and Campanula americana are synonyms defined as:

tall bellflower and Campanula americana: annual or perennial of eastern North America with long spikes of blue or white flowers

tall bellflower (noun)	Campanula americana (noun)
annual or perennial of eastern North America with long spikes of blue or white flowers	annual or perennial of eastern North America with long spikes of blue or white flowers