[1] In general, KMDF supports drivers that were written for the Windows Driver Model, and it runs on WDM.
WDM is the driver model used since the advent of Windows 98, whereas KMDF is the driver framework Microsoft advocates and uses for Windows 2000 and beyond.
In general, since more features like power management and plug and play are handled by the KMDF framework, a KMDF driver is less complicated and has less code than an equivalent WDM driver.
KMDF is object-based and built on top of WDM.
It provides an object-based perspective to WDM, following the architectural mandate of its superset, WDF.