Hi Julie,

Happy to provide my perspective as a former BCG Lateral Hire Interviewer.

First, It is important that you understand the background of this question, that means why it is being asked.

Situation
As lateral hire you are “thrown” into a working system where you have, compared to regular new hires, less time to come to speed with the way a consulting firm operates: How is the team coordinated, how is the client relationship being managed, how are internal stakeholders like Partners managed etc.

Complication
Since you are joining at a higher level, you need to effectively support the team as soon as possible despite that disadvantage. 

Question
That is why the interviewer would like to inquire if you have a solid understanding of what your consulting work will entail and how it differs from what you have done previously.

Second, let us look at what a good answer would include.
Essentially, you should be able to tell the challenges (answer the question directly) in order or priority (what is most challenging). You could then explain in more detail what fundamental skills and experiences you could already develop or demonstrate in the domain of that challenge - do not sell yourself short. However, demonstrate some awareness of the specifics of the ways of working in consulting by pointing out to some gap. If possible, provide initial ideas on how you will bridge the gap (e.g. by seeking feedback on client interactions from Partners to get their senior perspective).

Some further tipps
1. Make sure to tailor your points to the position that they offer to you or that you have applied to. E.g., differences in team leadership are much more relevant if you join as Project Leader than if you join as Consultant.
2. Reach out to your network and talk with active BCGers about what your role would entail to deepen your understanding. Besides roles and tasks, be aware of the high workload and time pressure.

I hope that could help. All the best for your 2nd roud!

Best,
Gero