For sure, the kind of clients they work with, the kind of work they do, and the salaries and working lives of their employees are all much closer to one another than to other firms.
However, as with any business, they remain the sum of their individual staff. This being the case, different offices will show some variation in terms of culture, focus, etc..
- McKinsey has historically been very strong in strategy, organization and operation work, and has the larger footprint in the Education, Public Sector and Telco space. That said, by virtue of its larger size, McKinsey usually has the deeper roster of client relationships across most industries.
- BCG sells itself as focusing on corporate development, innovation and business growth.
- Bain has the deepest expertise in working with Private Equity funds and other principal investors.
McKinsey leads in terms of overall size and reach, with over 9,000 consultants globally. This is followed by BCG, with7,000 consultants, and then Bain, with 4,000 consultants. By virtue of being considerably bigger than BCG or Bain, McKinsey boasts the most diverse footprint and larger office network. This disparity is most strongly felt in emerging markets, such as Sub-Saharan Africa and Latin America, where McKinsey has built a much stronger local presence than BCG or Bain. Across Europe and North America, the differences are less pronounced, but it's wise to check the office sizes for your desired cities before making decisions (for instance, BCG is particularly strong in some German cities).
The organization in McKinsey is a bit more traditional, formal and hierarchal, while BCG is flatter and more collaborative. Bain, on the other hand, is effectively a mix of both McKinsey and BCG, and the employee culture is a bit more "fratty". Of course, the three firms draw from the top schools worldwide - particularly top 10 business schools for their MBA hires - so there is a substantial overlap in the profiles of their hires.
In terms of travel, McKinsey has the most "global" approach. This means it's more likely for consultants from that firm to be staffed in projects based in offices other than their own. This is good if you enjoy the jet set lifestyle and accumulating airmiles - but sub-optimal if you want the stability of staying close to your home country. Regardless of firm, though, most consultants travel for four days a week, so it is simply a part of the job you will have to get used to.
Salaries, Career, and Opportunities:
In contrast to salaries, there are some meaningful differences in exit opportunities between the MBB firms. As the strength of particular firms’ networks vary across different industries, so your chances of breaking into those industries will vary as a result. Bain has the deepest network with PE and hedge funds, while McKinsey has broader connections with most traditional industries and public sector organizations.