Go carts sure have come along way in the last few decades. Especially the off road carts. The biggest difference between on and off road buggies are quite noticeable. First of all, the off road version is much larger. Some of them are large enough to seat two adults comfortably. Typically, though, they seat one adult or a large child. The larger design gives a good indication to which age range is best suited to drive them. If the child is not large enough to reach the controls then they are likely too small to drive it. Furthermore, the safety harness and other features will not fit the smaller child either.
Another apparent difference is the engine. Small street carts have a much smaller engine. These are usually in the 2 1/2 to 10 horsepower range. On the other hand, the off-road go cart can be found with engines as large as 1200 cc. The reason for these larger motors is power, not speed. If the vehicle has less than enough power, it will never make it up the hill. It can also be bogged down in the mud or sand. Navigating up the side of an embankment without enough power is dangerous. The vehicle could eventually come to a stop and then begin to roll backwards down the hill. Therefore, if the cart will be driven in steep terrain, be sure to choose a model with a large motor.
The tires are also very different on the off road models. They are taller for better ground clearance. This is important when navigating through rough and hilly terrain. Anyone that has ever been stuck on the side of a mountain knows it can be quite inconvenient as well as dangerous to get the vehicle unstuck. Next, the rear tires are much wider. This gives the vehicle better traction in mud and sand. Front tires are sometimes smaller but have large ribs as compared to the street models. This provides for better maneuvering. In addition, the suspension is different. The off road models have beefier suspension for greater stability and control in rough terrain.
Finally, the off road go carts have an aggressive styling with decals and a big roll bar. Some of them even come with a full roll cage for additional safety. All of these extra features make the off-street go-cart look more like a dune buggy, which the younger folks like.