While I've never been to the UK, so this is mostly based on weeks of intensive BBC America-based research, I would assume bullying is worse in the US. In my experience, school administrators in America just don't have the necessary balls to do anything about bullying, and I at least hope that the situation is different in the UK. Even if that doesn't hold true, the UK seems to generally have a more tolerant culture than the US. Obviously the cultural differences aren't that huge, but a slight difference can have a pretty big overall impact.