cIOS stands for Custom IOS, Ioses are what the wii runs off of and basiclly tells the wii what to do (From my understanding could be wrong) The custom means that it has been tampered with (hacked) so that we can do what we want with it and tell it what to tell the wii to do,MIOS is basiclly the wii going into gamecube mode and wii mode gets turned off so anything wii related wont work (usb, wiimotes,etc) Which is why we can't make a usb gamecube loader without a hardware mod or someone would have to rewrite all of MIOS which would be a lot of work.