nand writing problem

please i have a problem with programing a nand flash

i use rt809h to read and write read

i read a file[firmware file] from a nand have 01Gb storage memory

and i write it on other memory have the same storage space but it's not from the same manufacter

and where i place it on the device it's do not power on

here i try to read the software again from the new nand flash

now i found the problem the new file read it it's have'nt the same size with the original file size

the original nand can power on the device normaly

the originale nand it's from gigadevice and i try others nand from many manufacters [WINBOND.ESMT.FORESE]

the size of the original file is 139Mb on computer , where i write it on other nand and i read it again i found 135Mb only

i try to write a small[30Mb] file on the other memory and i try to read it again i found a file with the same size 135Mb

please i really need help the device is off have a month