What is the difference between application server and web server?

Question

What is the difference between application server and web server?

Answer 1

All of the above is just over-complicating something very simple. An application server contains a web server, an application server just has a couple more additions/extensions to it than standard web servers. If you look at TomEE as an example:

CDI - Apache OpenWebBeans
EJB - Apache OpenEJB
JPA - Apache OpenJPA
JSF - Apache MyFaces
JSP - Apache Tomcat
JSTL - Apache Tomcat
JTA - Apache Geronimo Transaction
Servlet - Apache Tomcat
Javamail - Apache Geronimo JavaMail
Bean Validation - Apache BVal

You will see that Tomcat (Web container/server) is just another tool in the app servers arsenal. You can get JPA and the other tech in the web server as well if you want, but the application servers just package all of these things for your convenience. To be fully classified as an app server you essentially need to comply with a list of tools set forth by some standard.