Pension value is known to be lower in East Germany than in West Germany. By 2025, pensioners in East and West should receive the same pension.
The decisive factor is where the pension rights were acquired as a pensioner. Widow's pension depends on the retirement pension of the deceased or on his or her disability pension. Widows and widowers living in the West can keep a little more of their additional income, which is credited to the pension. If you move from west to east, you have to expect a lower allowance in the new federal states.