Difference and purpose of const T *p and T *const p?

Question

C++ / C#

Why do we need pointers to a constant data type and a constant pointer to a data type, and what is the difference?

Answer 1

const T *p - the pointer can be changed, the data it points to is not.
T *const p - the pointer cannot be changed, but the data can be changed.
Usage - e.g. implementing the principle of least privilege