Hi leonardoprates,
Well usually the main difference is the speed of the boot-up During the card initialization, the ROM boot code attempts to set the boot partition for all
SD, eSD, and SDXC devices. If this fails, the boot code assumes that the card is a normal
SD or SDXC card. If it does not fail, the boot code assumes it is an eSD card. After the
initialization phase is over, the boot code switches to a higher frequency (25 MHz in the
normal-speed mode or 50 MHz in the high-speed mode).
Fastboot is a protocol used to update the flash filesystem in Android devices from a host over USB. It allows the flashing of unsigned partition images.
Hope this helps you.
Regards,
Israel.
