Luke vs St. Luke

Luke and St. Luke both are nouns.

Word	Noun	Adjective	Verb	Adverb
Luke	Yes	No	No	No
St. Luke	Yes	No	No	No

As nouns, Luke and St. Luke are synonyms defined as:

Luke and St. Luke: (New Testament) the Apostle closely associated with St. Paul and traditionally assumed to be the author of the third Gospel

Other synonyms of Luke include Luke the Evangelist, Saint Luke.

Luke (noun)	St. Luke (noun)
one of the four Gospels in the New Testament; contains details of Jesus's birth and early life	(New Testament) the Apostle closely associated with St. Paul and traditionally assumed to be the author of the third Gospel
(New Testament) the Apostle closely associated with St. Paul and traditionally assumed to be the author of the third Gospel