postgresql difference between two datetime code example

Example 1: postgres date difference seconds

-- difference in seconds between two dates

select extract(epoch from ('2020-03-30 09:55:56'::timestamp - '2020-03-30 08:54:55'::timestamp));
-- result : 3661

Example 2: postgresql get difference between two dates

select age('2010-04-01', '2012-03-05'),
       date_part('year',age('2010-04-01', '2012-03-05')),
       date_part('month',age('2010-04-01', '2012-03-05')),
       date_part('day',age('2010-04-01', '2012-03-05'));