Santa Claus vs Saint Nick

Santa Claus and Saint Nick both are nouns.

Word	Noun	Adjective	Verb	Adverb
Santa Claus	Yes	No	No	No
Saint Nick	Yes	No	No	No

As nouns, Santa Claus and Saint Nick are synonyms defined as:

Santa Claus and Saint Nick: the legendary patron saint of children; an imaginary being who is thought to bring presents to children at Christmas

Other synonyms of Santa Claus include Father Christmas, Kriss Kringle, Saint Nicholas, Santa, St. Nick.

Santa Claus (noun)	Saint Nick (noun)
the legendary patron saint of children; an imaginary being who is thought to bring presents to children at Christmas	the legendary patron saint of children; an imaginary being who is thought to bring presents to children at Christmas