Hi Anonymous A,
thank you for asking your question on our Consulting Q&A!
I found some other Q&As that might be interesting for you on the differences between first and second/final round:
Chern (received offers from McK and BCG):
The key differences between the 1st and 2nd interview rounds, besides the interviewers being principals or partners as you mentioned, are in structure, focus and selectivity. [...]
The structure in the 2nd round will most likely not follow the standard fit + case interview format. Partners may prefer to launch into a conversation about the latest developments in a particular business, industry or geography and talk about your motivations and life experiences later. Note they'll still expect you to layout your thoughts and communicate "top down" by leading with headline "insight" statements. This is the difference between being structured yet adaptable and being formulaic.
The focus in the 2nd round will likely be influenced by your performance in the previous round. The 2nd round interviewers will test on any areas where they perceived you needed to work on (e.g., more quantitative problem solving if you struggled with math in the 1st round, more creative brainstorming if you had difficulty coming up with tailored approaches and ideas to problems in the 1st round, etc.).
The selectivity in the 2nd round is much lower, as this is the round where hiring decisions are made. It may seem obvious but the stakes are higher and it requires all 3 partners to agree that you've met the bar, which explains the low acceptance rate (~1-3%) at the top 3 firms.
In short, the 2nd (final) round is more creative, yet structured, more focused on your development, yet still supportive (interviewers are there to help you succeed, not fail) and more selective, yet fair.
My recommendation is to practice unorthodox cases with a focus on your 1st round feedback and on preserving structure & communication no matter the subject or interview style, so that the interviews may catch you unawares but never unprepared.
Matteo (Mckinsey consultant focused on Digital & Technology applied to Business):
from my experience I believe there are 2 key differences between a first round and a second round, at least regarding Mck, Bain and BCG.
1) during the first round the interviewers will be senior managers and/or junior partners, whether in the second round you will generally meet senior partners or directors
2) Therefore since the two profiles mentioned above have a different seniority during the first round it is more likely that you will be asked more analytical questions and the business cases will be more detaild (e.g. estimate the market share at the endo of the third year knowing that.. ecc.), on the other side in the second round the you might have to tackle more broad and strategical questions (e.g. what would you outsource in a marketing department)
For the full Q&As and further info, please check the following links:
I hope this helps! If you have any further questions, don't hesitate to ask on our Q&A.
Best of luck and success for your last round interview,