mvebu/x530: Difference between spl/u-boot-spl.bin and spl/u-boot-spl-dtb.bin

Hello!

I would like to ask, what is the difference between spl/u-boot-spl.bin and spl/u-boot-spl-dtb.bin binaries?

Because there is board/alliedtelesis/x530/kwbimage.cfg file which overrides global file arch/arm/mach-mvebu/kwbimage.cfg.in and the only difference between these files is that board specific file uses spl/u-boot-spl-dtb.bin instead of spl/u-boot-spl.bin.