Pope Pius XI vs Pius XI

Pope Pius XI and Pius XI both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pope Pius XI	Yes	No	No	No
Pius XI	Yes	No	No	No

As nouns, Pope Pius XI and Pius XI are synonyms defined as:

Pope Pius XI and Pius XI: pope who signed a treaty with Mussolini recognizing the Vatican City as an independent state (1857-1939)

Other synonyms of Pope Pius XI include Achille Ratti, Ambrogio Damiano Achille Ratti.

Pope Pius XI (noun)	Pius XI (noun)
pope who signed a treaty with Mussolini recognizing the Vatican City as an independent state (1857-1939)	pope who signed a treaty with Mussolini recognizing the Vatican City as an independent state (1857-1939)