No, same roads. The vehicles just act differently. Steering, acceleration, those are nice and tight on the car. I zip-zoom-fly. But the 7,000 pound truck (which is just an extended cab long-bed F250 drives differently. If I take the same turn that I did in my car in my truck I'd flip the truck.I have to slow down more to turns. It takes me longer to brake, longer to accelerate. The vehicle does matter, as driving style is somewhat changed. You're more conservative in a truck because you can't see around as well and can't speed up to get out of someone's way like a car. If a sharp curve is coming up, you probably slow down to even what the signs say you should be at rather than ignoring them like I do when driving my car. It's just very different. My car handles faster speeds. It handles them with more control. And with less mass it's safer. Vehicles do differ - which is why some people buy sports cars and some people buy SUV's. If you want fast and performance suspensions you want the sports car and you can do things others can't. If you get the SUV you can carry an entire soccer team while pulling a boat, but you won't have the speed or driving characteristics of the sports car. It'll turn slower, you'll have higher chances of being a rollover. You just can't pick two different cars that different and pretend they're the same and that one-size-regulation makes it so. Some of those big SUV's towing trailers wouldn't dare go the speed limit out of safety, but they could (and be a danger).
The best person to decide how safe something is, is the driver. They learn the vehicle, they learn how it works, whether it drifts to the right or left, whether the mirrors work worth a damn, how long to stop, how fast to accel, and use that information to do what they feel is safe driving. It's not just a matter of "60MPH"