Talking more about the Kernel Mode and User Mode driversThe differences, I will continue to read and write about. These Kernel Mode Drivers continue to work as a part of Windows Executive and the provide inherent support to Windows Operating System Level Kernel mode functionality such as I/O, PnP, Processes, Threads, Security and memory and so on ..
Some Kernel mode drivers can be the WDM drivers. They Conform to the needs of Windows Driver Model, I mean they support the PnP Architecture and also the powr management. Important hint is these WDM drivers support the source on most Windows platform but they are not binary compatible. My understanding is they need to be recompiled once on the specific DDK.
Based on the fuctionality the Kernel mode drivers can be distingushed beteween three major categories.
1) Highest level drivers
2) Intermidiate level drivers
3)Lowest level drivers.
This diagram will make the ideas more clear.
The Highest level drivers can be examplified as file system drivers (FSDs) such as NT, FAT or CDFS driver. They are system supplied. (If you want you can try the expensive Installable file System Kit from Microsoft.) These type of drivers have a very high level of dependency on one or more lower level(other two types) drivers. Lets say at least the PnP Hardware bus driver.