SELECT
    X.DESCRICAO,
    Y.ID,
    X.FB_ADMIN_ID,
    CASE
        WHEN X.FB_ADMIN_ID = Y.ID THEN '-- EQUAL --'
        WHEN X.FB_ADMIN_ID IS NULL OR Y.ID IS NULL THEN '-- NULL --'
        WHEN X.FB_ADMIN_ID <> Y.ID THEN '-- DIFF --'
        ELSE '-- UNKN --'
    END AS MATCH
FROM
    TBSERVIDOR X
LEFT JOIN
    TBFIREBIRD_ADMIN_DB Y ON X.FB_ADMIN_ID = Y.ID

ORDER BY X.DESCRICAO;