polar circle vs Arctic Circle

polar circle and Arctic Circle both are nouns.

Word	Noun	Adjective	Verb	Adverb
polar circle	Yes	No	No	No
Arctic Circle	Yes	No	No	No

polar circle (noun)	Arctic Circle (noun)
a line of latitude at the north or south poles	a line of latitude near but to the south of the north pole; it marks the northernmost point at which the sun is visible on the northern winter solstice and the southernmost point at which the midnight sun can be seen on the northern summer solstice