Norman French vs Old North French

Norman French and Old North French both are nouns.

Word	Noun	Adjective	Verb	Adverb
Norman French	Yes	No	No	No
Old North French	Yes	No	No	No

As nouns, Norman French and Old North French are synonyms defined as:

Norman French and Old North French: the medieval Norman dialect of Old French

Other synonyms of Norman French include Norman-French.

Norman French (noun)	Old North French (noun)
the medieval Norman dialect of Old French	the medieval Norman dialect of Old French