Polaris vs polestar

Polaris and polestar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Polaris	Yes	No	No	No
polestar	Yes	No	No	No

As nouns, Polaris and polestar are synonyms defined as:

Polaris and polestar: the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward it

Other synonyms of Polaris include North Star, polar star, pole star.

Polaris (noun)	polestar (noun)
the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward it	the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward it