That's a big question... All consulting is 'C', climbing from 1 to 5, then you're at VP level, SVP, CVP.
A, B, etc gradings aren't used in Capgemini Consulting (at least in the UK) but are in other business units / geographies. A lot of the different areas have grown up differently, as acquisitions, etc, so the grading varies a lot.
From VP onwards grades are fairly consistent, but until then I believe there are about 9 A grades to the 5 Cs... so you can roughly map them across. Lots more promotions available, but smaller steps, obviously.