Pope Leo XIII vs Leo XIII

Pope Leo XIII and Leo XIII both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pope Leo XIII	Yes	No	No	No
Leo XIII	Yes	No	No	No

As nouns, Pope Leo XIII and Leo XIII are synonyms defined as:

Pope Leo XIII and Leo XIII: Italian pope from 1878 to 1903 who was interested in the advancement of learning and who opened the Vatican secret archives to all scholars

Other synonyms of Pope Leo XIII include Gioacchino Pecci, Giovanni Vincenzo Pecci.

Pope Leo XIII (noun)	Leo XIII (noun)
Italian pope from 1878 to 1903 who was interested in the advancement of learning and who opened the Vatican secret archives to all scholars	Italian pope from 1878 to 1903 who was interested in the advancement of learning and who opened the Vatican secret archives to all scholars