There are more than one concept to take the measure of a beer. Hops influence the bitterness, malts determine the sweetness. Finally, the alcohol content provides one last dimension to the brew.
Unlike wine, the majority of beers are not brewed to age. Beer typically spoils within a few months, a year at most, with rare exceptions. Even specialty brews aren't made to improve over the five, ten or even longer age of some fine wines. There are some specialty brews, though, that can age up to 30 years.