The first technical round is a generic programming interview to see if you're a good programmer. They ask about your experience and specifics, but most of the focus is on your problem solving skills. The first technical round was a very positive experience, it makes it seem they're looking for good professionals who can adapt to any situation. They seem to trust you to adapt to new technologies as long as your smart.
Then you're hired.
And then you have to take further job interviews for the potential projects you could join, and later also with the clients of those projects. These are the complete opposites of the first interview. These are the interviews where you'll get questions like "Have you worked with our exact same technology stack for multiple years?" These interviews are the same as the more strict specialist job interviews, you're treated like an outsider.
When you get an offer from Epam and you accept it, you should still not cancel your other applications until you passed the inside interviews. Even though you're technically hired, your job is not guaranteed until that point.