It is generally agreed that there are two broad subcategories of beer- ales and lagers. The main difference between the two is the type of yeast used to ferment them. A lager is any beer made with bottom fermenting yeast in cool temperatures. An ale is any beer made with top fermenting yeast at warmer temperatures.

---> Ale yeasts ferment at warmer temperatures  (between 60 and 75°F).

---> Lager yeasts ferment at colder temperatures  (45 to 55°F).

The warmer fermentation temperature of ales promotes the production of both a more complex, full bodied flavor as well as aromatic compounds with a much bolder presence. {Compared to the more crisp flavor profile of a lager whose yeast is "cooked" at a lower temperature}. In a nutshell, ales offer a more intense flavor for a very simple reason:  If the yeast is "cooked" to a higher temperature, it's full range of flavor potential is reached. .... Almost like letting a red sauce, for example, simmer slowly for hours.

The colder fermentation temperature of lagers can actually inhibit flavor complexities and aromatic compounds in beer. This is why lagers tend to have a lighter, cleaner, and more crisp flavor profile than ales tend to have.