Comparing two rows in PostgreSQL
instead of dblink, I recommend you to use potgres_fdw.
When you map the foreign table, you can use a simple SELECT INSERT to solve your problem. E.g.:
INSERT INTO remote.employee
SELECT local.* FROM public.employee AS local
WHERE NOT EXISTS ( 
     SELECT 1 FROM remote.employe AS remote
     WHERE local.id = remote.id
)


Remember to fix the WHERE filter to fit your table's primary keys.

EDIT: I make a small sample how to compare the rows of both tables as a gist: https://gist.github.com/sebastianwebber/7b4ab352733e8aab8b03f94d8aa0c7a9

The easy way to compare the rows is:
SELECT
    e1.id as e1_pk,
    e2.id as e2_pk,
    COALESCE(e1.* = e2.*, false) as equal
FROM employee1 as e1
RIGHT JOIN employee2 as e2 USING (id);


Hope it helps.