Alpha Centauri vs Rigil

Alpha Centauri and Rigil both are nouns.

Word	Noun	Adjective	Verb	Adverb
Alpha Centauri	Yes	No	No	No
Rigil	Yes	No	No	No

As nouns, Alpha Centauri and Rigil are synonyms defined as:

Alpha Centauri and Rigil: brightest star in Centaurus; second nearest star to the sun

Other synonyms of Alpha Centauri include Rigil Kent.

Alpha Centauri (noun)	Rigil (noun)
brightest star in Centaurus; second nearest star to the sun	brightest star in Centaurus; second nearest star to the sun