The accusations come from O'Reilly & Associates, a California IT book publisher and online content and software provider, that has emerged as a fierce critic of Microsoft business practices. They are based on an article by Andrew Schulman, a senior editor at O'Reilly who is best known as the author of "Unauthorised Windows 95", a book that delves deep into Microsoft OS code in search of programming secrets.
Schulman claims that the Workstation and Server versions of NT share the same kernel and are differentiated only by two registry settings in version 4.0 and only one in version 3.51, despite the fact that the 10-user version of NT Server 4.0 costs several hundred pounds more than NT Workstation 4.0.
O'Reilly claims this is significant as Microsoft has been marketing the products as being significantly different and has been restricting usage on the Workstation version of the product, saying the product is unsuitable for heavy multi-user usage. Schulman calls the price difference "little more than a Web tax".