Ursa Minor vs polar star

Ursa Minor and polar star both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ursa Minor	Yes	No	No	No
polar star	Yes	No	No	No

Ursa Minor (noun)	polar star (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