As Jason recently posted, we spent Thursday evening at the Monarch/World Class Beverages facility. Our trip out wasn't just for a tour; We also sat in on World Class' salesperson training where we learned about Real Ales, Firkins, Fruit Beers and Strong Ales from World Class' professional beer geek, Bob Mack.
Real Ales and Firkins
According to the folks at Campaign for Real Ale (CAMRA), real ale is "is a natural product brewed using traditional ingredients and left to mature in the cask (container) from which it is served in the pub through a process called secondary fermentation." This container can be a cask, firkin, bottle or even an aluminum can - the defining characteristic is that the beer is matured by secondary fermentation in the container in which it is dispensed.
Often times you'll hear real ales refered to as "firkins". By definition, a firkin is a container (made of any material) for real ale that holds 10.8 gallons of real ale (9 imperial gallons, or 1/4 a British beer barrel). So while a real ale can also be a firkin, a firkin is not necessarily a real ale.
 Unfortunately, we can only aspire to be professional beer geeks. Good work if you can get it.