Leo XIII vs Pope Leo XIII

Leo XIII and Pope Leo XIII both are nouns.

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

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

Leo XIII and Pope 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 Leo XIII include Gioacchino Pecci, Giovanni Vincenzo Pecci.

Leo XIII (noun)	Pope 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