pilot bread vs ship biscuit

pilot bread and ship biscuit both are nouns.

Word	Noun	Adjective	Verb	Adverb
pilot bread	Yes	No	No	No
ship biscuit	Yes	No	No	No

As nouns, pilot bread and ship biscuit are synonyms defined as:

pilot bread and ship biscuit: very hard unsalted biscuit or bread; a former ship's staple

Other synonyms of pilot bread include hardtack, pilot biscuit, sea biscuit.

pilot bread (noun)	ship biscuit (noun)
very hard unsalted biscuit or bread; a former ship's staple	very hard unsalted biscuit or bread; a former ship's staple