combat zone vs combat area

combat zone and combat area both are nouns.

Word	Noun	Adjective	Verb	Adverb
combat zone	Yes	No	No	No
combat area	Yes	No	No	No

As nouns, combat zone and combat area are synonyms defined as:

combat zone and combat area: a military area where combat forces operate

combat zone (noun)	combat area (noun)
a military area where combat forces operate	a military area where combat forces operate
a city district known for its vice and high crime rate