polar circle vs latitude

polar circle and latitude both are nouns.

Word	Noun	Adjective	Verb	Adverb
polar circle	Yes	No	No	No
latitude	Yes	No	No	No

As nouns, latitude is a hypernym of polar circle; that is, latitude is a word with a broader meaning than polar circle:

Other hypernyms of polar circle include line of latitude, parallel, parallel of latitude.

polar circle (noun)	latitude (noun)
a line of latitude at the north or south poles	scope for freedom of e.g. action or thought; freedom from restriction
	the angular distance between an imaginary line around a heavenly body parallel to its equator and the equator itself
	an imaginary line around the Earth parallel to the equator
	freedom from normal restraints in conduct