The media is very different, and performs completely different functions. They may sometimes look similar, but a catalytic media actually performs a chemical reaction on the substances in your airstream, reducing HAPS and VOCs to CO2, Nitrogen, O2, and water. The media in an RTO is a heat sink, and does not remove harmful substances from air. In an RTO, the temperature in the combustion chamber is what causes the VOCs to oxidize. The media is used as a means of pre-heating the air coming into the oxidizer to reduce the use of your support fuel.