blue star vs Amsonia tabernaemontana

blue star and Amsonia tabernaemontana both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue star	Yes	No	No	No
Amsonia tabernaemontana	Yes	No	No	No

As nouns, blue star and Amsonia tabernaemontana are synonyms defined as:

blue star and Amsonia tabernaemontana: subshrubs of southeastern United States forming slow-growing clumps and having blue flowers in short terminal cymes

blue star (noun)	Amsonia tabernaemontana (noun)
subshrubs of southeastern United States forming slow-growing clumps and having blue flowers in short terminal cymes	subshrubs of southeastern United States forming slow-growing clumps and having blue flowers in short terminal cymes