Ales vs Lagers

Simply put, ales are fermented/brewed at higher temperatures than lagers. As a result, a wider range of chemical components are solubilized and extracted, resulting in more complex flavor profiles. Lagers are brewed at lower temperatures and result in cleaner, less complex flavors.

You can think of it like brewing coffee. Cold brews (which take longer) result in smooth, mild, less acidic coffee. Hot brew coffees tend toward sharper, more bitter taste due to the higher extraction of acids and volatile compounds.

Here is a deeper dive into the subject.