Based in part on personal experience, as well as that of colleagues at both IBM and CG, I suspect you will find a stronger traditional consulting culture at CG than at IBM. That is CG, as was typically the case with the old big 5, value is placed on the people who are empowered to perform in such a way as to optimise the results of the organisation. At IBM greater emphasis is placed on the brand and the organisation of resources, such that operational excellence becomes the competitive edge. Good luck !