Is there a difference between creating tf.Variable and keras.layers.Layer.add_weight()

I've seen both approaches in Tensorflow documentation:

#1

class MyDenseLayer(tf.keras.layers.Layer):
  def __init__(self, num_outputs):
    super(MyDenseLayer, self).__init__()
    self.num_outputs = num_outputs

  def build(self, input_shape):
    self.kernel = self.add_weight("kernel",
                                  shape=[int(input_shape[-1]),
                                         self.num_outputs])

  def call(self, inputs):
    return tf.matmul(inputs, self.kernel)

#2

class Linear(keras.layers.Layer):
    def __init__(self, units=32, input_dim=32):
        super(Linear, self).__init__()
        w_init = tf.random_normal_initializer()
        self.w = tf.Variable(
            initial_value=w_init(shape=(input_dim, units), dtype="float32"),
            trainable=True,
        )
        b_init = tf.zeros_initializer()
        self.b = tf.Variable(
            initial_value=b_init(shape=(units,), dtype="float32"), trainable=True
        )

    def call(self, inputs):
        return tf.matmul(inputs, self.w) + self.b

Is there a fundamental difference between creating a variable with self.add_weight() or tf.Variable() inside your custom layers? Examples are taken from https://www.tensorflow.org/tutorials/customization/custom_layers and https://www.tensorflow.org/guide/keras/custom_layers_and_models respectively.