CLIENT SERVER :In client server application you have two 
different components.Application is loaded on server 
machine while the application exe on every client 
machine.This environment is used in intranet networks.you 
are aware of clients and servers and thier location in test 
scenario.

WEB BASED:It is a bit different and complex application is 
loaded on the server whose location may or may not be known 
and no exe is installed on the client machine.