def _nullable_list_symmetric_difference(list_1, list_2):
    """
    Returns the symmetric difference of 2 nullable lists.
    
    Parameters
    ----------
    list_1 : `None` or `list` of ``DiscordEntity``
        First list.
    list_2 : `None` or `list` of ``DiscordEntity``
        First list.
    
    Returns
    -------
    symmetric_difference : `None` or `list` of ``DiscordEntity``
        A list with the two list's symmetric difference.
    """
    if list_1 is None:
        if list_2 is None:
            return None
        
        else:
            return list_2.copy()
    
    else:
        if list_2 is None:
            return list_1.copy()
    
    symmetric_difference = set(list_1) ^ set(list_2)
    if not symmetric_difference:
        return None
    
    return list(symmetric_difference)