There are bullies in all walks of life, of all ages. Generally there are fewer bullies at uni because people do grow up. I think the transitional years between finishing high school and going to uni allow a lot of people to grow up, and then actually getting to uni gives a fresh start. The people who are bullies at uni, I think anyway, are just not very nice people. High school bullies tend to do it to fit in as much as anything else.
If somebody is bullying you, ask them why they're doing it. Don't make a scene, get them on their own. They might not realise what they're even doing, or might think they're being funny. I certainly wouldn't stand for it at uni, though, because people should definitely have grown up by that point.