Character varying(n) vs text

CREATE OR REPLACE FUNCTION public.random_func(min_val INTEGER, max_val INTEGER) RETURNS INTEGER AS
$BODY$begin
  RETURN min_val + round((max_val - min_val) * random());
END;$BODY$
LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION public.random_func_str(str_len INTEGER) RETURNS CHARACTER VARYING AS
$BODY$declare
  RESULT CHARACTER VARYING = '';
BEGIN
  FOR i IN 1..str_len loop
    RESULT = RESULT || chr(random_func(65,90));
  END loop;
  RETURN RESULT;
END;$BODY$
LANGUAGE plpgsql;

CREATE TABLE public.table_char
(
  id INTEGER NOT NULL,
  str CHARACTER(32),
  CONSTRAINT table_char_pk PRIMARY KEY (id)
);

CREATE TABLE public.table_varchar
(
  id INTEGER NOT NULL,
  str CHARACTER VARYING(32),
  CONSTRAINT table_varchar_pk PRIMARY KEY (id)
);

CREATE TABLE public.table_text
(
  id INTEGER NOT NULL,
  str text,
  CONSTRAINT table_text_pk PRIMARY KEY (id)
);

INSERT INTO table_char(id, str)
SELECT gs, random_func_str(32) FROM generate_series(1,1000000) gs;

INSERT INTO table_varchar(id, str)
SELECT gs, random_func_str(32) FROM generate_series(1,1000000) gs;

INSERT INTO table_text(id, str)
SELECT gs, random_func_str(32) FROM generate_series(1,1000000) gs;

SELECT
   relname AS "Table",
   pg_size_pretty(pg_total_relation_size(relid)) AS "Size",
   pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) AS "External Size"
   FROM pg_catalog.pg_statio_user_tables ORDER BY pg_total_relation_size(relid) DESC;

EXPLAIN analyze
SELECT id, str FROM table_text WHERE str LIKE '%ABCD%';