The up-side is that the time from brewing to finished product is shortened, thereby boosting productivity. Heat Pasteurized is a redundant phrase since pasteurization means heating to kill microbes. Some beers are bottle or cask conditioned, meaning that live yeast are still in the beer in its container. Most mainstream beers are either filtered, to remove all yeast and bacteria, or pasteurized to kill all yeast and bacteria. This makes for a more stable product with a longer shelf-life.
Pasteurization is more expensive and tends to alter the flavor.
Filtration is cheaper, leaves a clearer beer, and has less effect on flavor. Technically speaking, draught beer is beer served from the cask in which it has been conditioned. It has been applied, loosely, to any beer served from a large container. More recently, it has been used as a promotional term for canned or bottled beer to try to convince us that the beer inside tastes like it came from a cask.