This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Personally, of those two products I would use Tomcat for any and all purposes for which it stretches itself. The main difference between Tomcat and Sun's application server is that, well, Tomcat is a web container while the Sun product is a full application server.