Updraft Range Hoods are units which sit above your range or cooktop that pulls the smoke, air and grease upward into the unit. Due to the location of the blower they are audible when in operation. The exhaust is then vented outside.
Downdraft Range Hoods are built underneath your range or cooktop. They draw air from underneath and often have a blower located below the range. These units run much more quietly.
Cabinet Insert Hoods are installed into a custom slot within the cabinetry. This provides you with the functionality of a range hood combined with a more sleek appearance. These are also known as insert liner range hoods.
Blowers are responsible for powering the hood. They are required on most hoods and downdraft systems. Some hoods come with a blower attached but be sure to check your owner's manual.