KVM (kernel-based virtual machine) is based on QEMU but with added features. Most notably, KVM utilizes virtualization hardware (if available) through the use of kernel modules that are specific to each hardware platform. This makes KVM much more efficient compared to QEMU on platforms that support virtualization.
All options that apply to QEMU also apply to KVM. This makes any conversion of scripts intended for QEMU a trivial matter: just change the command from qemu to kvm.