What is the big difference between Windows 2000 Server and Windows 2000 Small Business Server?

Small Business Server is a turnkey network solution designed for (wait for it...) small businesses that bundles the Windows 2000 Server operating system with several productivity, messaging and Internet applications, with the caveat that it is limited to 50 concurrent workstation connections.

From Microsoft.com: "Small Business Server 2000 is a full-featured network solution that delivers a unified setup...

for e-mail and group scheduling, fax, database, shared Internet connectivity and more. Designed for flexibility, you can use Small Business Server to deploy and use components and features at your own pace and to focus on your business, not your technology. Specifically, Small Business Server 2000 includes:

• Microsoft Windows 2000 Server. The operating system providing file, print, Web, application and management services.
  
• Microsoft Exchange 2000 Server. The messaging and collaboration server delivering 'anytime, anywhere' access to the people and information you want.
  
• Microsoft Internet Security and Acceleration (ISA) Server 2000. The server providing an extensible firewall with a Web cache server and policy-based security, acceleration and management of shared Internet connections.
  
• Microsoft SQL Server 2000. The database server supplying fast, reliable relational database management server and engine for running a multitude of business software solutions.
  
• Microsoft Shared Fax Service. The best way for sending and receiving faxes and providing support for fax boards, Integrated Services Digital Network (ISDN) cards and broadcast fax.
  
• Microsoft Shared Modem Service. The service that enables client computers to use modems shared on Small Business Server to connect to external information services.
  
• Microsoft Health Monitor version 2.1. The service for sending server status and advance warning of potential problems.
  
• Microsoft FrontPage 2000. The Microsoft Office tool for creating and managing Web sites.
  
• Microsoft Outlook 2000. The Office client for messaging and collaboration."