My point of view:
The best example of pure Web Server is Apache. You can also use another definition as HTTP server or Web Container which serves using HTTP methods (mostly GET and POST).
Application server is a set of containers:
- jsp/servlet container ( Tomcat
has both:web and jsp/servlet containers);
, JMS, JMX containers (JBoss
WebLogic App Server has Web, EJB, JMX and JMX containers.
App Server is like a set of services with useful admin console and some useful features as load balancing, transaction, authentication and authorazation.
Tell me if I wrong.