What is the difference between CHARACTER VARYING and VARCHAR in PostgreSQL?

John uses CHARACTER VARYING in the places where I use VARCHAR. I am a beginner, while he is an expert. This suggests me that there is something which I do not know.

What is the difference between CHARACTER VARYING and VARCHAR in PostgreSQL?

VARCHAR is an alias for CHARACTER VARYING, so no difference, see documentation :)

The notations varchar(n) and char(n) are aliases for character varying(n) and character(n), respectively. character without length specifier is equivalent to character(1). If character varying is used without length specifier, the type accepts strings of any size. The latter is a PostgreSQL extension.

The PostgreSQL documentation on Character Types is a good reference for this. They are two different names for the same type.

The only difference is that CHARACTER VARYING is more human friendly than VARCHAR