Is there any difference between Achara Dharma and Atma Dharma ?

They are not the same. Achara Dharma is a lower form of Dharma. Its purpose is to elevate one to the platform Atma Dharma(or Sanatana Dharma). Achara Dharma can be loosely translated as morality whereas Atma(or Sanatan)Dharma can be translated as the eternal religion of the Soul. Morality does not always indicate Spirituality, whereas Spirituality(in its pure form) is inclusive of morality. Morality makes it easier to access Spirituality.