CODE:

------snip------
struct S {
        int[] data;
}
void main() {
        auto s = S([1,2,3]);
        auto t = S([1,2,3]);
        auto u = S([1,2,4]);

        assert(s == t);
        assert(s != u);
        assert(typeid(s).compare(&s, &t) == 0); // FAILS
        assert(typeid(s).compare(&s, &u) != 0);
}
------snip------

Since S doesn't define opEquals or opCmp, the typeinfo's .compare is just the default provided by DMD. However, it uses bitwise comparison, whereas == uses field-wise comparison.