All I know about differences of them is
varchar has limit, and
text is not. The documentation does not mention about this.
Is that really the only difference? No consideration about performance or etc?
The background of this is: The old Postgres system used the PostQUEL language and used a data type named
text (because someone thought that was a good name for a type that stores text). Then, Postgres was converted to use SQL as its language. To achieve SQL compatibility, instead of renaming the
text type, a new type
varchar was added. But both type use the same C routines internally.
Now, to some degree and in some places,
text is hardcoded as a default type, in case nothing else can be derived. Also, most functions are only available as taking a
text argument or returning
text. The two types are binary compatible, so casting is a trivial parse-time operation. But using
text is still overall more natural to the system.
But aside from these fine points, there is no noticeable difference. Use whichever one looks prettier to you. ;-)
See this similar question. The jist is that there is no difference, but specifying a maximum length such as
varchar(n) is generally not in your favor, as it uses more space but doesn't improve performance.
character varying(n), varchar(n) variable-length with limit text variable unlimited length
text without declared length. There are no performance differences between these two types.