What is the difference between a macro and a const in C++?

Question

I was asked this question in a technical interview:

What is the difference between a const and a macro in C++?

My a

Answer 1

define can be redefine , but const will be cause compiler error:

sample: source : main.cpp

#define int_constance 4
#define int_constance 8 // ok, compiler will warning ( redefine macro)

const int a = 2;
const int a = 4; // redefine -> error

int main(int argc, char** argv)
{
   std::cout << int_constance ; // if remove second #define line, output will be 8

   return 0;
}