There are many different types of beers; however, ales and lagers are the most common varieties, with many subtypes within each of those varieties. While they aren’t set in stone, there are simple differences in color, taste and alcohol content between the two varieties. The major difference between ale and lager comes down to just two brewing details: yeast and temperature.
Ale is fermented using Saccharomyces cerevisia, a common yeast type that is also used in wine and breadmaking. The fast action of this yeast species brews the ale in as short as a week, with the yeast products floating to the top due to the increased motion within the fermentation vessel. Lager is fermented using Saccharomyces uvarum. This yeast isn’t so much bottom-fermenting; but it doesn’t rise to the top as an ale yeast will before settling to the bottom as fermentation winds down. It also attenuates sugars more slowly, causing the brewing process to move more slowly. Compared to ale yeast, it is a much more fragile yeast that requires more specific conditions to thrive.
Top-brewing ales tend to be brewed at higher temperatures, usually between 60-80°F, with some unusual varieties going as high as 95-100°F. For this reason, ales are typically brewed in these ranges to quickly bring it through the fermentation cycle due to the increased chemical activity at the higher temperatures. Lagers are fermented at colder temperatures, usually around 42-55°F. Fermentation happens more slowly at lower temperatures, meaning lagers take longer to brew because their fermentation process is not as fast. The lower temperature for lager means the yeast produces fewer aroma and flavor compounds.
Lager is named for the German word lagern which means “to store.” Traditionally brewed in caves throughout central Europe, the cold temperatures meant the beer would be kept for a longer period of time at a cool temperature as compared to ale’s warmer storage in other parts of the world. This step allowed more of the yeast, proteins and hops to settle out of the lager, improving clarity dramatically and reducing chill haze. Nowadays, lagers still need to go through a similar storage and maturation process, unlike ales which can be ready to drink in a much shorter time.
Although hops are present in almost every beer style, they tend to be in different quantities in an ale compared to a lager. In a lager’s cold treatment process, the finer flavors of the hops are able to come out and provide a more delicate flavor. By comparison, hops tend to be found in much higher content in ales, leaving a more bitter taste. Lagers usually have a cleaner, crisper taste, while ales are more often richer, deeper, more complex or “funkier.”
No matter what type of beer it is, the yeast will directly impact the overall alcohol content. Since ale yeast is much hardier in higher-alcohol environments, it will survive into higher levels of alcohol, causing ales to have a higher alcohol content. By comparison, the slower, more fragile lager yeast generates less alcohol because it can’t survive beyond that lower alcohol content, causing lagers to generally have a lower alcohol content.
Overall, ales tend to be darker, have a cloudier appearance, higher alcohol content and a stronger, fruitier, more robust flavor. Ales will have stronger bitter tones due to the higher amount of hops, along with a faster and more thorough fermentation. Lagers tend towards a lighter, clear appearance, and have a lower alcohol content. Lagers have a sweeter, smoother, crisp flavor from the higher sugar content, slower fermentation and go through a cold treatment. These characteristics are all strongly affected by the yeast, brewing practices and post-fermentation handling that play a role in the final product.