memory allocation for nk.bin



hi?
I'd like to understand the difference between nk.bin and nk.nb0.
Bin file is compressed format and nb0 is pure binary so for executing
directly without any uncompression the nb0 file would be needed. But
actually, the bin file is loaded to SDRAM and can run from the sdram.
How the compressed bin file can run at SDRAM?
.