Difference between Application Server and Web Server

Hi guys n gals,
I m not sure about the difference between the application server and web server. The following is the basic difference that I know. Please correct me if m wrong.
Application Server : Application server is where ur jsp's and servlets reside. Such as servletrunner and tomcat.
Web Server : Web server is where u keep your html pages and java class files for applets if any. Ex. IIS, Apache WebServer.
Tomcat is an application server. I have found a webserver.jar file in tomcat. Am i wrong ? Is tomcat a webserver too ? or the file is for internal use of tomcat to configure tomcat with several web servers.
I successfully configured tomcat with iis 5 on win 2000. But if tomcat itself is a web server what I did is of no use it seems. (except for gaining knowledge).
Please give your replies and lets make an effort to define both the terms for newbies. So that no one gets confused in future.

nitin

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A web server does web services, like you said, serving up HTML and other resources.
An application server is a web server PLUS functions like servlets etc. - Tomcat can be a web server although it is not as fast at serving plain pages as IIS. Plenty of people are using Tomcat for both.
To some extent, "Application Server" is a marketing buzzword, but it does indicate capabilities beyond serving plain pages.

There are several diff. b/n a webserver and an appserver
-A webserver in simple terms is a fileserver that works on the HTTP protocol.It doesn't do any processing on it's own like a database access,or running an external program like CGI\servlets...each of such external programs need their own run-times or 'engines' to be installed on the webserver to enhance it's functionalities.
-An appserver like Weblogic ,Websphere has much more capabilities like
1)It has built-in support for running servlets/jsp's/ejb's.nothing needs to be installed separately.
2)Muli-tiered enterprise applications developed in jsp's/ejb's can be hosted(deployed) on an appserver.
3)It can maintain a pool of open connections to a datasource and supply them to a client request on demand.This significantly speeds up the appl. bcoz of the time saved in opening a db connection upon each request.
4)it has support for XML.
5)An appserver works in conjunction with one or more webservers at the same time.many webservers can route their incoming requests to an appserver and the appl. hosted on the appserver then proceses this request.this technique(ofcourse with a lot more details and configurations needed) does the work of managing the 'load' the appl. is handling.
there are many more interesting features of an appserver.Interested persons can check out the sites of Weblogic or WEbsphere or any other popular appserver.
Hope this helps,
Girish