The most obvious difference between ale and lager beer is the type of yeast used in the fermentation process. Ales are fermented with top-fermented yeast at warm temperatures (60° to 70° F), while lagers ferment with lower-fermented yeast at cold temperatures (35° to 50° F). The word lager comes from the German word meaning “store”, as lagers were first stored in cold caves to mature. Lager yeasts prefer cooler temperatures (about 42-55℉), ferment more slowly and are considered “bottom fermenters”.
Ale yeasts prefer warmer temperatures (about 60-75℉) and are considered “top fermenting” depending on the location of fermentation activity in a fermentation tank. In terms of taste, ale has a more fruity taste, while lagers have a more crunchy taste that is not so sweet. Because lager yeasts were among the first to be isolated in their pure form without wild contamination, lager beers originally had a longer shelf life. The arrival of refrigeration allowed the brewing of lager beer throughout the year.
In comparison, slower and more fragile lager yeast generates less alcohol because it cannot survive beyond that lower alcohol content, resulting in lagers generally having a lower alcohol content. Hops are present in almost every style of beer, but it tends to be in different amounts in an ale compared to a lager beer. In the cold treatment process of a lager beer, the finer flavors of hops can come out, providing a more delicate flavor without sacrificing the additions that hops can make to the finished beer. Lagers span a variety of styles, including pale Pilsners and German Helles and darker American beers. Lagers also go through an extra step that beers don't go through, one of cold conditioning to develop greater clarity.
There are blond beers that are as pale as classic Czech pilsners (a lager), and smooth and dark lagers like schwarzbiers that are as opaque and black as stouts (an ale). Although there are many different types of beer, with ale and lager being the most common varieties with many subtypes within each of these varieties, it is easy to find a beer that satisfies almost any palate.