It is a 32 bit operating system and uses a flat 32 bit memory address model. The operating system controls all the hardware. In fact it does so to the point that the BIOS is only used to load the boot strap program that will load the Windows NT operating system. After that, everything is Windows NT code, so each piece of hardware must have a Windows NT driver. If it doesn't have a driver, it simply is not supported.
Many older programs take direct access to the hardware to improve speed.
Often, they write directly to the video card to speed performance, and NT does not allow this, as it is a threat to the stability of the system. The two are mostly identical, but Workstation is optimized for single user and fast application response, while Server is optimized for fast network response. Currently, the PCs in the WAM labs have Windows NT Workstation version 4.0 installed. There are no Windows NT Server WAM machines, thus things unique to NT Server will not be covered in this document. There is a lot more to Windows NT then initially meets the eye though.