Wall Hung toilets are suspended from the floor and require a wall frame for mechanical support. The wall frame is usually hidden within a wall, a cabinet or 'boxed in' using MDF or plasterboard and tiled.
Floor Standing units are designed to sit on the floor, with the back flush to a cabinet. They require an separate concealed cistern fitted within the cabinet.
Close Coupled toilets are a more traditional style toilet, with a visible, usually porcelain cistern sat on the back on the pan.