Typically, when buses are involved in collisions, be it a school bus or a motorcoach, they're the larger vehicle involved in the collision and the injuries are more serious in the other vehicles.
Collision dynamics are very different when you go from a front-end collision to a T-bone type of collision, but anecdotally, when a bus hits a larger vehicle, there's going to be more damage to the bus, as opposed to when it is struck by, say, a pickup truck or a passenger car.