A highway is a road with a higher speed limit. It thus features plenty of points for entry and exit onto the highway, with loads of intersections. You might come across toll booths, traffic lights, road signs, or perhaps rail and pedestrian crossings. Combined with its wider accessibility, highways are often a lot more congested. Meanwhile, freeways are more restricted in access. Yet, they don't have plenty of intersections or crossings that would interrupt traffic flow. With that in mind, freeways allow more motorists to drive on them at a time. And, at far higher speeds than you'd get on a highway.