Application server and web server in Java both are used to host Java web applications. Though both the application server and web server are generic terms, the difference between the application server and the webserver is a famous J2EE interview question. From on Java J2EE perspective, the main difference between the web server and application server is the support of EJB. In order to run EJB or host enterprise Java application (.ear) files, you need an application server like JBoss, WebLogic, WebSphere, or Glassfish, while you can still run your servlet and JSP or java web application (.war) file inside any web server like Tomcat or Jetty.