Http Server , Web Server:
1. httpServer & WebServer are same Ex.: Apache, IIS, iplanet
2. This serves only static content like html Pages & images
3. WebServer can handle only Http requests & responses
4. There are also Servers , Servlet containers like Tomcat that can serve both static & dynamic content by using Jsps & Servlets.
Application Server:
1. Application Server contains a webServer & a container. container processes dynamic web content. & webserver for transferring the static pages.
Ex: weblogic & WebSphere.
2. Application Server primarily exposes business logic to various client applications.
3.ApplicationServers can Handle requests through other protocols.
4.Application Server can provide lots of other ancillary services like connection pooling, Transaction handling.