Does the method of assignment change how memory is allocated?

I had this code

const char* value = retCharPtrFunc();

Which had to be changed to:

const char* value;
if (true)
value = (retStringFunc()).c_str();
else
value = retCharPtrFunc();

And for some reason now this code is accessing more heap memory than before. Heap memory is for pointers (dynamic alloc.) and it doesn't look like I have added more memory than before, just changing the assignments.

Is there any difference how these code are interpreted and allocated memory?

signature of retCharPtrFunc()

const char* retCharPtrFunc() const;

string retStringFunc() const;