The first round is all behavioral and its 1 on 1 with a hiring manager or somebody who helps/runs the area that you are applying for. The second round is a case interview that isn't your traditional MBB format. Instead, its more like they give you a scenario and you have to come up with a solution for it.

I had my first round interview 3 weeks ago. It was a hybrid behavioral & case interview. I got extended to the second round case interview. Don't stress the first round. I didn't expect to have a case study during the latter half of the interview, but the interviewer walked me through it.