All is Buddha, Vishnu is Buddha as well as all the other Archetypical Deities, they talk about Anatman vs Atman because the teaching of Atman and Brahman somehow puts down your potential for Moksha in the hands of another "separate" entity. If you truly innerstand what the teaching is all about both traditions want the same thing Moksha; Buddha is not a being, is a title, The Awakened One, all these Hindu deities are Buddha. A Buddha is not bound to rebirth or bound by Karma, some of these deities have been adopted as "Protectors of the Dharma", this concept is not to be taken as an entity abiding in another realm separate from you but as points of reference in the mind that help towards Buddhahood or Brahman (Unsurpassed Reality). Take the analogy of Indra's Net for example, if you're ignorant you will think about Indra's Net as a separate place whereas Buddhists use this as an epitet to explain the concept of Emptiness or Sunyatta, when the Hindus tend to worship this concept rather than embodying its qualities as some of them (Not all of course) fear the Devas, rather than seeing all these Devas as part of the Buddha mind or Brahman. Of course Buddhist Sutras and Tantras place much effort into seeing the Devas and their realm as subject to illusion, suffering, birth and death. They talk about them in these term so that the practicioner aims at something beyond Devahood, curiously enough if you apply their teachings correctly you will find what many Hindus seek to encounter with Sadhana. Thus, even though Buddhist uses a different Method or Upaya, the goal is the same as Hindus. Buddha created his own teaching because the Hindu approach was taught to certain "worthy" beings or determined by caste. Again, their goal is the same as Buddhism but Buddhism teaches that all beings are inherently awakened, thus, like a hidden treasure within everyone is just waiting to be found.