The major difference is salary
In general, Strategy& is more close to MBB in the US than in the other countries.
- Salaries - Strategy& will have similar salary on a post-MBA level but lower partner salary (although more tiers for partners)
- Career progression may be slower at Strategy& (at least compared to McKinsey)
- Subjectively, the quality is higher at MBB. However, the Strategy& is close, especially if the partner is ex MBB
- Knowledge base- MBB knowledge bases are extremely deep and helpful. You have tons of materials on various topics.
- Support - at MBB you will have lots of people taking care of extra staff - doing research, the visual design of slides, sophisticated models, outsourcing for making surveys in the field. At Strategy& you'll do that stuff yourself
- Benefits - you will have better hotels, better dinners, better airline tickets, etc at MBB. This is important if you spend 90% of your life out of home
- Exposure to senior management may be higher, though it depends on the country. Since the projects are more expensive at MBB, you may have more senior people involved