The spacecraft portion of ITS is being designed for interplanetary travel. Skylon, as I already said, is confined to Earth orbit, with the air-breathing space-p

The spacecraft portion of ITS is being designed for interplanetary travel. Skylon, as I already said, is confined to Earth orbit, with the air-breathing space-plane portion confined to LEO. (It only gets stuff to GTO or GEO with the payload-bay booster, which is a purely conventional rocket.)