insert into <Таблица_1>
    select * from <Таблица_2>
        EXCEPT select * from <Таблица_1>

MERGE <Таблица_1> AS T1
USING <Таблица_2> AS T2
    ON T1.ID = T2.ID
WHEN NOT MATCHED BY TARGET
    THEN INSERT(ID, ...) VALUES(T1.ID, ...);