nautical signal flag vs code flag

nautical signal flag and code flag both are nouns.

Word	Noun	Adjective	Verb	Adverb
nautical signal flag	Yes	No	No	No
code flag	Yes	No	No	No

As nouns, nautical signal flag and code flag are synonyms defined as:

nautical signal flag and code flag: one of an international code of flag signals used between ships

nautical signal flag (noun)	code flag (noun)
one of an international code of flag signals used between ships	one of an international code of flag signals used between ships