polar front vs cold front

polar front and cold front both are nouns.

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

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

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

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