Why is copying pairs slower than copying structs?

I wanted to show my team why move semantics can save resources. So I wrote some code to get some numbers for the talk. However, during this work I found something interesting which I did not fully understand. Copying a vector of pairs took substantially longer than copying a vector of an equivalent struct. Any ideas why?

Output:

std::pair<int,int>
===============
- sizeof type: 8
- sizeof container: 16
- copy = 80392 microseconds
- move = 6 microseconds

PAIR
====
- sizeof type: 8
- sizeof container: 16
- copy = 6377 microseconds
- move = 8 microseconds

Code:

#include <iostream>
#include <vector>
#include <chrono>

template <typename T>
void
MoveCopyComp()
{
    std::vector<T> list;
    T dummy;
    std::cout << "- sizeof type: " << sizeof(T) << "\n";
    std::cout << "- sizeof container: " << sizeof(list) << "\n";
    for (int num = 0; num < 1000000; ++num)
        list.push_back(dummy);

    auto t0 = std::chrono::steady_clock::now();
    std::vector<T> copy = list;
    auto t1 = std::chrono::steady_clock::now();
    std::vector<T> movement = std::move(list);
    auto t2 = std::chrono::steady_clock::now();
    std::cout << "- copy = "
              << std::chrono::duration_cast<std::chrono::microseconds>(t1 - t0).count()
              << " microseconds\n";
    std::cout << "- move = "
              << std::chrono::duration_cast<std::chrono::microseconds>(t2 - t1).count()
              << " microseconds\n";
}

struct PAIR
{
    int a;
    int b;
};

int main(int argc, char **argv)
{
    std::cout << "std::pair<int,int>\n===============\n";
    MoveCopyComp<std::pair<int,int>>();
    std::cout << "\nPAIR\n====\n";
    MoveCopyComp<PAIR>();
}