combat area vs combat zone

combat area and combat zone both are nouns.

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

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

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

combat area (noun)	combat zone (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