web application is n-tier application
client/server application is the two tier application.

Client-Server Application
- both client and server exist within the walls of single 
company, thus operated in a protected environment
- so, client becomes a trusted user
- clients can be controlled as who can access and use 
server's resources within a company's firewall
- network protocols are considered like TCP/IP,UDP,ARP etc

Web Application
- it is a specialized version of client-server model
- client can connect to server from anywhere thus not a 
single connection can be treated as trusted
- to control clients is tough as anyone with a browser can 
access the Web application
- protocols and standards like HTTP,HTML,XML,SOAP etc are 
used

Client server Technology:
1. Number of clients is predicted or known
2. Client and server are the entities to be tested
3. Both server and client locations are fixed and known to
the user
4. Server to server interaction is prohibited
5. Low multimedia type of data transaction 
6. Designed and implemented on intranet environment
7.Application is loaded at the server. In every client
machine, an exe is loaded to call this application. 


In client server testing test engineer are conduct the
following testings:-
1.Behaviour testing(GUI TESTING)
2.Input domain testing
3.Error Handling testing
4.Backend testing


Web based Technology
1. Number of clients is difficult to predict (millions of
clients)
2. Client, Server and network are the entities to be tested
3. Server location is certain, client locations are not certain
4. Server to server interaction is normal
5. Rich multimedia type of data transaction 
6. Designed and implemented on internet environment.
7. Application is loaded at the server.but,No exe is
installed at the client machine. We have to call the
application through browser.

In Web testing test engineer are condut the following testings:-
1.Behaviour Testing
2.Static web testing
3.Input domain testing