Windows NT comes in two different versions: Server, and Workstation. Both are the same, however licensing and packaging is different. The Server version gives more priority to server processes, bundles server programs, and has a licensing agent. Workstation gives user applications priority while limiting the number of simultaneous connections to that one computer to 10.
Windows NT is fully 32-bit, despite it's Windows 3.1 appearance. It is completely unrelated to the other line of Windows OSes.

While NT can run behaved DOS and 3.x programs using a subsystem, NT programs cannot be run on Windows 3.x because 3.x is a 16-bit cooperative-multitasking operating system. A thing called "Win32s" was a limited set of NT APIs made available for 3.1 that allowed it to run limited numbers of NT programs with limited featuresets because a few features simply were not possible win 3.1. Windows 95 integrated the majority of the NT framework into Windows 3.1.

Unlike Windows 3.1, NT has fully protected user support, and you are unable to access the system without logging on. A login username and password may be verified with either the local machine, a local domain, or a master domain that is trusted.

After logging in, the Program Manager comes up.
Apart from being user-aware, the NT Program Manager, as mentioned in my NT 3.1 review, is not much different from the Windows 3.1 program manager.

One thing I did not mention previously is the presence of those icons in the lower-right corner of the program groups, and what they meant. The ones with the head are program groups that may be modified or deleted by the user and be totally unaffected by other users. The computer indicates a common program group, which contains items that cannot be modified by anyone but the system administrator(s), and are the same for all users.

Since NT 3.51 does not run on top of DOS, it has to include it's own disk utility, which is shown above. It supports creating, moving, resizing and deleting NTFS and FAT partitions. Keep in mind however that this is before FAT32 and exFAT support was even in Windows.

Also shown in this screenshot is the Performance utility. NT was designed to be performance-critical, and this utility allows you to see the performance ratings for individual parts of the PC/operating system.

Here is a shot of the Event Viewer, and the User Manager which allows you to create users, edit permissions, set groups, enable auditing for certain users, and delete users.

The file manager is basically the same as that of Windows 3.1, except it contains some permission changing options.