I know the basic difference like debug has debug information & release have better opt settings.

1. But in embedded, debug info always remains with host, only hex files gets burned to target MCU. So what difference it made.

2. I have tried many different codes with debug or release. In both, code generated is always same. I never find it different.

3. Is there any parameter/token/macro defined in compiler settings for deug?

 

In the debugger in MPLAB there is a small shadow program placed into upper memory, smaller or lower end Pic's require a piggy-back board to provide storage and communication when using in debug mode.
In program mode only the compiled hex code of the program is entered.
Max.