You can't judge a bock by its color
James Rodewald has an interesting snippet article in Gourmet this month about beer. It's a very short primer that basically says: Don't be scared. Beer is simple. (If it were complicated, it wouldn't have survived all of these tens of thousands of years, after all.)
Marketing language aside, Rodewald says, water isn't what makes beer special (even though it is mostly water). The flavor comes from a variety of grains, hops and yeasts, handled in different combinations and permutations for the dizzying array of beers available today.
But, at its simplest, all beer is either lager (pilsner and bock, for example) or ale. Ale is brewed with powerful yeasts that work quickly and provide full, fruity flavors. Lager yeasts ferment more slowly and consequently don't add as much flavor. (As a result, lagers tend to showcase the other ingredients in the beer more.)
Of course, at its most complicated, lagers and ales come in every shade and color. But that's what makes it so fun to learn!