C++: What is the difference between std::set and std::multiset?

1// set — unique
2std::set<int> s;
3s.insert(1);
4s.insert(1);  // Ignored
5
6// multiset — duplicates allowed
7std::multiset<int> ms;
8ms.insert(1);
9ms.insert(1);  // Stored
10ms.count(1);  // 2