How do I get the number of different or common elements between two vectors of strings?

Is there a function to compare two string vectors to return the number of different (or the same) elements? Do I have to iterate over both of them and test item by item?

// C++20
std::ranges::sort(v1);
std::ranges::sort(v2);
std::vector<std::string> v3;
std::ranges::set_intersection(v1, v2, std::back_inserter(v3));

// any version
std::sort(v1.begin(), v1.end());
std::sort(v2.begin(), v2.end());
std::vector<string> v3;
std::set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), std::back_inserter(v3));

Or, if you don't want to sort:

std::set<std::string> s1(v1.begin(), v1.end());
std::set<std::string> s2(v2.begin(), v2.end());
std::vector<std::string> v3;

// C++20
std::ranges::set_intersection(s1, s2, std::back_inserter(v3));
// any version
std::set_intersection(s1.begin(), s1.end(), s2.begin(), s2.end(), std::back_inserter(v3));

You may want to use a multiset if there could be duplicates in a vector.