Mark vs St. Mark

Mark and St. Mark both are nouns.

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

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

Mark and St. Mark: Apostle and companion of Saint Peter; assumed to be the author of the second Gospel

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

Mark (noun)	St. Mark (noun)
the shortest of the four Gospels in the New Testament	Apostle and companion of Saint Peter; assumed to be the author of the second Gospel
Apostle and companion of Saint Peter; assumed to be the author of the second Gospel