Bochs is apowerfulx86/amd64hardwareemulation anddebuggersoftware. Besides the CPUand instructset extensions,it simulatescommon PC/AThardware, anISA and PCIsystem bus,memory, disks,video hardware,ethernet, andenough of acompatible BIOSto runDOS/Winows,Linux/BSD,Minix and otheroperatingsystems. Itdoesn'tprovidevirtualization,thus runsextremely slow,but is safe torun for thehost operatingsystem.
QEMU is ageneric machineemulator andvirtualizer. Itcan emulateother CPU andhostarchitectures,or run nativebinaries withnativeperformances byexecuting theguest codedirectly on thehost CPU anyonly emulatedevices.It's thusoften used inconjunctionwith KVM onLinux forsystemvirtualization.