polar zone vs Frigid Zone

polar zone and Frigid Zone both are nouns.

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

As nouns, polar zone and Frigid Zone are synonyms defined as:

polar zone and Frigid Zone: the part of the Earth's surface forming a cap over a pole; characterized by frigid climate

Other synonyms of polar zone include polar region.

polar zone (noun)	Frigid Zone (noun)
the part of the Earth's surface forming a cap over a pole; characterized by frigid climate	the part of the Earth's surface forming a cap over a pole; characterized by frigid climate