A web server is where usually web components are deployed, ie. this will provide a run-time environment for these components. Web components can be a jsp file or Servlet. Here for deployment we use web.xml file.
where as in application server we can deploy an java components ranging from simple java application to server side business components like ejbs. Usually when we want to deploy EJBs we will go for App servers like weblogic or websphere. Here ejb-jar.xml or application.xml file is used as deployment descriptor.
Double check with your audience that you're talking about the same things. Maybe include very short definitions in footnotes in written docs.
Our Internet Engineering guys say "web server" for Apache or IHS. Anything that runs Java is "application server" to them. This confused the heck out of us for a long while ... we call Apache the HTTP server, the servlet container the web server and the EJB container the app server. Now we know to verify our assumptions when we talk to them!
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi