Size Of C++ Allocation Is More Than C

If you use the same code, simply change the compiler (from a C compiler to a C ++ compiler) to change the amount of memory allocated. I do not know why and I would like to understand better. So far, the best answer I’ve received is “probably the I / O streams”, which is not very descriptive and puzzles me on the aspect “you do not pay for what you do not use”. Can you tell me where I am wrong?
