What’s the difference between aep version and aes version

[SSTPE]

I am attempting to downgrade a Cisco C8500L-8S4X from c8000aes-universalk9.17.12.05a to c8000aep-universalk9.17.09.03a.But failed evertime.So I want to know the difference between two versions.

%ERROR% Booting an incompatible image for this platform
Failed to boot file bootflash:c8000aep-universalk9.17.09.03a.SPA.bin

Thank you for your help.

[M02@rt37]

Hello @SSTPE 

I'm gonna check but from my knowledge,  C8500L-8S4X cannot boot c8000aep images, because they are "designed" for earlier or different 8500 variants, or for 8300/8200 series...