North Star vs polar star

North Star and polar star both are nouns.

Word	Noun	Adjective	Verb	Adverb
North Star	Yes	No	No	No
polar star	Yes	No	No	No

As nouns, North Star and polar star are synonyms defined as:

North Star and polar star: 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 North Star include Polaris, pole star, polestar.

North Star (noun)	polar star (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