What's the difference between parentheses and braces in c++ when constructing objects

What's the difference between () and {} when constructing objects?

I think {} should only support with initializer_list or an array, but when I run below snip, I confused.

#include <iostream>
using namespace std;
struct S {
    int v=0;
    S(int l) : v(l) {
    }
};


int main()
{
    S s1(12); // statement1
    S s2{12}; // statement2
    cout << s1.v << endl;
    cout << s2.v << endl;
}

statement1 is right because () is the basic grammar for constructing the object.

I expect the statement2 will be compiled failed. I think {} is only can be used for an array or initializer_list type. but the actual result is compiled perfectly without error.

what do I miss?