European Community regulation N°216 set the rules to operate any aircraft in Europe.
The Annex number II of this regulation (page L79/32 & 33) set the aircraft categories which don’t have to comply with those rules (airworthiness, pilot license, maintenance approval, etc.).
Among other categories, like warbirds, vintage airplanes, ultralight motorized aircrafts, are mentioned:
(g) gliders with a maximum empty mass, of no more than 80 kg when single-seater or 100 kg when two-seater, including those which are foot launched;
Without calling it, this “g” paragraph defines the european ultralight glider, so as paragraph “e” defines the european motorized ultralight.
Indeed, if you add to an 80kg empty weight single seater the mass of a heavy pilot and the equipments (parachute recovery system, flight instruments), you get close to 200kg, which is a little less than the 220g maximum take off weight of the ultralight glider as defined by the FAI.
As a result of this exemption, each european state is free to set it’s own regulations for gliders within this mass limitations. Unfortunately, for example, Germany has adopted a very strict regulation threatening ultralight glider development in this country.
Note that EASA makes no differences if the glider is foot launchable or not. For the europeans authorities, ultralight gliders and hang-gliders are in the same deregulated category. Unfortunately, many european countries did only deregulate the foot launchable ultralight gliders.