shipping vs merchant vessels

shipping and merchant vessels both are nouns.

Word	Noun	Adjective	Verb	Adverb
shipping	Yes	No	No	No
merchant vessels	Yes	No	No	No

As nouns, shipping and merchant vessels are synonyms defined as:

shipping and merchant vessels: conveyance provided by the ships belonging to one country or industry

Other synonyms of shipping include cargo ships, merchant marine.

shipping (noun)	merchant vessels (noun)
the commercial enterprise of moving goods and materials	conveyance provided by the ships belonging to one country or industry
conveyance provided by the ships belonging to one country or industry