ship money vs customs

ship money and customs both are nouns.

Word	Noun	Adjective	Verb	Adverb
ship money	Yes	No	No	No
customs	Yes	No	No	No

As nouns, customs is a hypernym of ship money; that is, customs is a word with a broader meaning than ship money:

ship money: an impost levied in England to provide money for ships for national defense
customs: money collected under a tariff

Other hypernyms of ship money include custom, customs duty, impost.

ship money (noun)	customs (noun)
an impost levied in England to provide money for ships for national defense	money collected under a tariff