cold front vs polar front

cold front and polar front both are nouns.

Word	Noun	Adjective	Verb	Adverb
cold front	Yes	No	No	No
polar front	Yes	No	No	No

As nouns, cold front and polar front are synonyms defined as:

cold front and polar front: the front of an advancing mass of colder air

cold front (noun)	polar front (noun)
the front of an advancing mass of colder air	the front of an advancing mass of colder air