All beers can be broken down into two major categories- ale or lager beer. There are some major differences between the two when it comes to how the beer is fermented, and the flavor is different between the two types as well.
Ales are a type of beer that is fermented between 65 - 75 °F. Ales also use yeast that is “top fermented”. This means that the yeast tends to sit on top of the beer while it is fermenting, and works its way down as it eats. Ales tend to leave a taste on your palate for a long period of time, and to have a fruitier, more complex taste.
Wheat and Stout beers are also ales due to the fact that they ferment at room temperature and use top fermenting yeast. Most home brewers are going to make ales because of the temperature that they ferment at.
Due to the warmer temps, ales result in more ester production from the yeast. These esters are what create a fruitier, more complex beer. The taste of the beer doesn’t depend on the yeast being top or bottom fermenting.
Lagers are a beer that is fermented between 40 - 55 °F. Lagers use yeast that is “bottom fermented”’. Meaning the yeast will tend to sink to the bottom and work its way up as it eats. Lagers typically have a cleaner, smoother finish on your palate, meaning the flavor does not last on your tongue as long as an ale will. Most large commercial beers in America are lagers. Lagers can also include sub categories such as Bock, Pilsner, etc. because these styles of beer will use, and ferment, yeast just like lagers will.
Due to the cooler fermentation temperatures, most home brewers do not make lagers. It is ideal to use a refrigerator with an external thermostat to make lagers because you can control the temperature much better. Lagers will typically ferment slower than ales because the cooler temperatures will make the yeast work slower.
Hint: A way to get around the temperature issue of making a lager is to use your basement floor. If you have a vinyl or cement area in your basement, put a glass of water on the floor. Add a thermometer to the glass of water and let it sit for 24 hours. If the thermometer reads anywhere between 40-55 °F, then you can use your floor to make a lager.