>We have to move our server to NT, for several reasons.
>And we're puzzled : we don't know the technical diffrences between NT Workstation and NT server.
>

The principle differences are limitations on connects, support for fault tolerance disk options, and the ability to establish and manage a domain environment. The code, with minor exceptions, is the same - there are a couple of registry keys that enable or disable the features of NT Server that can't be easily manipulated by the user, and manipulating them incorrectly results in a completely unusable system.

Behaviorally, the allocation of memory and CPU resources is different under the two. I believe that stock NT WS can work with dual processor configurations; stock NT Server can handle up to 4 processors, and there are version that will support more.

NT Server Enterprise alters how the 4GB address space is allocated; rather than allocating 2GB to user application space and 2GB to operating system services, NT Server Enterprise makes 3GB available to user application space and limits the operating system space to 1GB. This in theory gives better performance in large NT Server installs running server applications.

A number of software components, especially BackOffice components, will only run on an NT Server platform.

A more complete comparison is available at http://www.ntfaq.com

>Anybody could help ?