Saint Nicholas vs Nicholas

Saint Nicholas and Nicholas both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Nicholas	Yes	No	No	No
Nicholas	Yes	No	No	No

As nouns, Saint Nicholas and Nicholas are synonyms defined as:

Saint Nicholas and Nicholas: a bishop in Asia Minor who is associated with Santa Claus (4th century)

Other synonyms of Saint Nicholas include St. Nicholas.

Saint Nicholas (noun)	Nicholas (noun)
a bishop in Asia Minor who is associated with Santa Claus (4th century)	a bishop in Asia Minor who is associated with Santa Claus (4th century)
the legendary patron saint of children; an imaginary being who is thought to bring presents to children at Christmas