I'm much in agreement with Chris's differentiator: state.

Web applications can have code executing on the workstation, even through the web browser. Examples are java applets, ActiveX controls, and even active scripting using VBScript or JScript, for instance. These do require an interaction between the workstation and server in these cases.

Citrix is defined as a thin-client, but except for the container, the ICA client, it doesn't require you to actively use anything on the workstation. Of course, file transfers, printer usage, and the like can blur this line again.

So you've got the case where web apps can fit the definition given for client-server computing and a thin client fitting the definition given for network computing.

Perhaps the line is so blurry that it's near impossible to separate systems into two distincts sets.

K. Brian Kelley

http://www.truthsolutions.com/

Author: Start to Finish Guide to SQL Server Performance Monitoring

http://www.netimpress.com/shop/product.asp?ProductID=NI-SQL1