Pius XI vs Pope Pius XI

Pius XI and Pope Pius XI both are nouns.

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

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

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

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

Pius XI (noun)	Pope 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)