Caret notation and control characters in Vim

Question

In Vim (or in a terminal?), control characters and their caret notation cannot be distinguished, like Enter vs. C-M. However, there is an only exception; BS vs. C-H.
Why are they only privileged?

For example, if you map Enter to NOP, also C-M will be mapped. Other many control characters have the same behavior. On the other hand, BS and C-H can be mapped to different keys respectively.

:map <Enter> <NOP> // also <C-M> will be mapped
:map <BS> <NOP>    // only <BS> will be mapped, <C-H> won't

Answer 1

You can insert a backspace into a file by pressing controlV before the backspace. In that case, vim (and most editors) will display it as ^H. But normally backspace is treated as a command (telling vim to do something, depending on the mode).

When moving the cursor in a file containing control characters, you can readily distinguish between a control character versus caret next to another character: as you move the cursor left/right, vim will move two columns for the control character, but one column for each of the caret and other character.