Both of these terms refer to the method used to reduce emissions and increase efficiency in wood stoves. Catalytic combustion has been used for years. It is very similar to what has been put on car exhaust systems to help them meet emissions standards. It is a chemical that makes the combustor ignite the gases that would have gone up the chimney as smoke. The gases are burned, creating more heat, as well as a cleaner burn and higher efficiency. A non-catalytic combustion system includes tubes that inject air into the firebox at strategic places and times to encourage more complete combustion. This system keeps the door glass clean, by injecting air to keep the smoke off the window, making it much more enjoyable to watch the fire. Non-catalytic is the newest technology in wood stoves.