basic differences are the following (keep in mind that for global firms I refer especially to MBB):
- type of work & projects: Global firms usually do shorter projects and a higher level (e.g. industrial plans). Is it common that boutiques come after such high level projects to start the actual implementation phase. So often boutique have more "practical" tasks (e.g. PMO). Boutiques are often very focused on an industry (e.g. insurance) or a function (e.g. finance), so is unlikely to see many different industries in such firms.
- travel: boutiques are usually very local, meaning that travel are usually inside the country where the firm is located. Global firms might require you to go wherever in the world, either because they need a very specific expertise which is only available in your local office or there is a shortage of resources in some specific, fast growing offices
- culture: this is very firm-specific, so there is no systematic differences between boutiques and global firm. In general, boutiques are less policy-driven, with more familiar environment, but local office of global firms are usually quite independent and when size is not too big they can still act like a boutique, of course with some constraints deriving from being part of a global network (e.g. feedback methods)
- salary: referring to MBB, salary in global firms is usually higher, I would say at least by 30% in low-mid levels (associate/consultant). Salary comparison at highest level is not very significant because is highly dependent on structure. Global firms usually have better benefits too.
- exit options...? Global firms are well recognized by any employer, whereas for boutiques your exit strategy are basically limited by the industry/function where the boutique has its core business. Moreover, you are expected to be hired in a better contractual position exiting from a global firm.