Uploading problem in my Arduino

Re: Uploading problem in my Arduino .

I found a silly mistake that wrong board (Arduino Nano) was found selected in TOOLs meny in Ide.. I corrected it by selecting Arduino UNO and uploading works without any errors.
Now my customised PCB also works fine.

Even though problem is solved I would still like to know how this matters, Is boot loading codes are different for different boards even tough Atmega AVR is same??

Thanks for helps.
Warm Reagards
SUBRAMANYA