merchant vessels vs shipping

merchant vessels and shipping both are nouns.

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

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

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

Other synonyms of merchant vessels include cargo ships, merchant marine.

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