My take is that Bruce is a strategist - he plans in advance, he sees the cheap move that turns an even match into a blowout, or the out-of-left field tactic that turns a losing situation on its head. Diana, on the other hand, is the tactician who knows the general best practices for a wide variety of common situations, can work out the best practices for a group with extremely unusual abilities, reacts to unanticipated events, and can easily follow Batman's reasoning when he comes up with a particularly twisty idea.