Armand Jean du Plessis vs Duc de Richelieu

Armand Jean du Plessis and Duc de Richelieu both are nouns.

Word	Noun	Adjective	Verb	Adverb
Armand Jean du Plessis	Yes	No	No	No
Duc de Richelieu	Yes	No	No	No

As nouns, Armand Jean du Plessis and Duc de Richelieu are synonyms defined as:

Armand Jean du Plessis and Duc de Richelieu: French prelate and statesman; principal minister to Louis XIII (1585-1642)

Other synonyms of Armand Jean du Plessis include Cardinal Richelieu, Richelieu.

Armand Jean du Plessis (noun)	Duc de Richelieu (noun)
French prelate and statesman; principal minister to Louis XIII (1585-1642)	French prelate and statesman; principal minister to Louis XIII (1585-1642)