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We can compare the definitions of any two tables using the following function:

CREATE OR REPLACE FUNCTION diff_table_definition
(t1_schemaname text
,t1_tablename text
,t2_schemaname text
,t2_tablename text)
RETURNS TABLE
(t1_column_name text
,t1_data_type text
,t2_column_name text
,t2_data_type text
)
LANGUAGE SQL
as
$$
SELECT
 t1.column_name
,t1.data_type
,t2.column_name
,t2.data_type
FROM
 (SELECT column_name, data_type
  FROM information_schema.columns
  WHERE table_schema = $1
      AND table_name = $2
 ) t1
 FULL OUTER JOIN
 (SELECT column_name, data_type
  FROM information_schema.columns
  WHERE table_schema = $3
      AND table_name = $4
 ) t2
 ON t1.column_name = t2.column_name
 AND t1.data_type = t2.data_type
WHERE t1.column_name IS NULL OR t2.column_name IS NULL
;
$$;