Roman law vs legal code

Roman law and legal code both are nouns.

Word	Noun	Adjective	Verb	Adverb
Roman law	Yes	No	No	No
legal code	Yes	No	No	No

As nouns, legal code is a hypernym of Roman law; that is, legal code is a word with a broader meaning than Roman law:

Roman law: the legal code of ancient Rome; codified under Justinian; the basis for many modern systems of civil law
legal code: a code of laws adopted by a state or nation

Roman law (noun)	legal code (noun)
the legal code of ancient Rome; codified under Justinian; the basis for many modern systems of civil law	a code of laws adopted by a state or nation