def hash_diff(old_hash, new_hash):
    """
    Returns the keys in new_hash that have different values
    in old_hash. Also returns keys that are in new_hash but not
    in old_hash.

    Keyword arguments:
        old_hash -- the dictionary of hashes for the old directory
        new_hash -- the dictionary of hashes for the new directory
    """
    paths_changed = []
    new_paths = []

    for key, value in new_hash.items():
        if key in old_hash:
            if value != old_hash[key]:
                paths_changed.append(key)
        else:
            new_paths.append(key)

    return (paths_changed, new_paths)