This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Apache webserver = webserver Tomcat = servlet container, but some say 'application server' since it hosts 'web applications'. Since you can host web resources such as HTML, gif, css etc. from Tomcat as well, tomcat can be used as both, but it is primarily servlet engine (or, an application server).