Only that it's going to be 'body and soul' hard work at any of the strat houses - it's just the nature of the job; it's intense. Fascinating, challenging, and rewarding, yes - but also intense. As to differences, you might find people articulating a view that BCG is more cerebral/conceptual/academic and Bain more data-driven/analytical/action-orientated, but these distinctions are very old: ADL begat BCG in the 60s, which begat Bain in the 70s, which begat LEK in the 80s and Parthenon in the 90s :) - it's inevitable that people try to talk up the differences when, objectively, the similarities might be the more striking. I'd still recommend choosing on the basis of the people, as you'll be spending an awful lot of time with them, but you could also look to understand the mix of work (sectors, type of engagement, length of project and working location) at the offices you might be joining.