free port vs free zone

free port and free zone both are nouns.

Word	Noun	Adjective	Verb	Adverb
free port	Yes	No	No	No
free zone	Yes	No	No	No

As nouns, free port and free zone are synonyms defined as:

free port and free zone: an area adjoining a port where goods that are intended for reshipment can be received and stored without payment of duties

free port (noun)	free zone (noun)
an area adjoining a port where goods that are intended for reshipment can be received and stored without payment of duties	an area adjoining a port where goods that are intended for reshipment can be received and stored without payment of duties
a port open on equal terms to all commercial vessels