Ursa Minor vs polestar

Ursa Minor and polestar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ursa Minor	Yes	No	No	No
polestar	Yes	No	No	No

Ursa Minor (noun)	polestar (noun)
a constellation outside the zodiac that rotates around the North Star, also known as the Little Bear or Little Dipper	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