polar zone vs North Frigid Zone

polar zone and North Frigid Zone both are nouns.

Word	Noun	Adjective	Verb	Adverb
polar zone	Yes	No	No	No
North Frigid Zone	Yes	No	No	No

polar zone (noun)	North Frigid Zone (noun)
the part of the Earth's surface forming a cap over a pole; characterized by frigid climate	the regions to the north of the Arctic Circle centered on the North Pole