No soul vs Atman

One of the things I'm familiar with in Buddhism, partucularly othordox Theravada Buddhism, is that because there is no such thing as a self there there is no such thing as an Atman. Buddhism claims that the Atman means that everyone has a seperate entity that goes from lifetime to lifetime. The more I look into it however, Hinduism doesn't claim the the Atman is a seperate enity at all, but that it's in line and connected to everything in the universe. In a way this is comparible to the Mahayana Buddhist concept of Buddha nature. To me Buddha nature at Atman seem to be the same thing, though just with different terminologies attached to it. Behind the illusion of ego lies our true nature, mahayana would call it Buddha nature, Hindu's atman.
Am I getting this right?