<human>:  What is the difference between ale and lager beer?
<bot>: The main difference between ale and lager beer is the type of yeast used in their fermentation process. Ales typically use top-fermenting yeast, which ferments at warmer temperatures and produces flavors that are more fruity, spicy and complex. Lagers use bottom-fermenting yeast that ferments at cooler temperatures and produces a cleaner and crisper flavor. Ales also tend to have a higher alcohol content than lagers.