N prefix and ::bpchar

Hello, I am not good at English.

I have a question.

There are the following data.

create table chartbl
(
caseno int,
varchar5 varchar(5)
);
insert into chartbl values(1, ' ');
insert into chartbl values(2, '');

The same result with the following two queries is obtained.
select * from chartbl where varchar5 = ' '::bpchar -- ::bpchar
select * from chartbl where varchar5 = N' ' -- N prefix

Is this specification?
Does it continue not to change?