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.
A component can be pretty much any kind of packaged functionality (anything from a single Java class to a group of 13 EJBs to a shell script -- even a Word document can pass the definition for a component) while a web service indicates that it's accessible over the Web using SOAP. In other words, "web service" is a more specialized term than "component".