This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
"Helpers" are just that--classes that help, like general utilities. A "handler" can be just about anything, like an HTTP request handler. They are very general terms and what they mean really depends on context.