Describe the differences in type deduction between decltype and auto. Give an example of an expression where auto and decltype will deduce the same type and an example where they will deduce differing types

`auto` will ignore the top-level `const` qualifier and reference.

`decltype` will include top-level `const` and reference.

Same type

    int i;
    auto a1 = i;     // int
    decltype(i) d1;  // int

Different type

    int i, &j = i;
    auto a2 = j;     // int
    decltype(j) d2;  // int &

    const int i;
    auto a3 = i;          // int
    decltype(i) d3 = 42;  // const int