Hi Anonymous,
The interview format tends to be more candidate-led - but it's anyway a differentiation that most candidates understand in a wrong way and practically makes not a big difference in general case interview prep (although it does in the dynamics of the interview).
At the same time there is no special focus - it's just as any other MBB case interview (except McKinsey, which indeed is more standardized).
For the phone interview screening - apart from the content-wise prep which you need to do anyway, just focus on the communication which needs to be even more ultra-clear than in on--site interviews (be even more structured, take longer breaks, speak slightly slower, ..).
Hope that helps - if so, please give it a thumbs-up with the green upvote button below!
Robert