The oneness of religions in terms of mystical experiences and shared insights derived from those experiences is important but the distinctiveness of them is also important. Sufism, Vedic mysticism, hesychasm (Eastern Christian mysticism), and Vipassana/Zen (Buddhist mysticism) all have similar meditative practices that lead to similar experiences. But they offer different interpretations of the meaning and significance of those experiences. I think that in the case of Buddhism, the differences from Vedanta are quite important because they have huge implications. Since Buddhism rejects the Vedas and the concepts of Brahman and atman, it means that Buddhists can very well be atheists. The differences here are very significant because they logically lead to fundamentally different worldviews. This can also lead to big differences in epistemology and ethics.