It's funny I keep typing a response, the proof reading and deciding to change. So defintitely not an easy question. Original can overlap with both survivor and restored, but a restored bike can never be a survivor.
Someone could be selling an 'original' bike that is in awful condition and in need of total restoration to run. But the engine/frame/tins, gauges etc are all the ones that came on the bike from new. So you can honestly say the bike is all original. Now you could restore it to as-new condition and call it restored original condition. Not the original paint, some new parts like mufflers or wheels, but by and large just the parts that came on the bike from Japan restored to original condition.
To me, to be a survivor, the bike needs to run, or be relatively easy to get running and retain the vast majority of its original from the factory parts. My '77 Goldwing is a good example of this. It's mostly as it came from the factory with the exception of the fairing and bags and king/queen seat. But the paint is original as are the shelter (faux gas tank) and sidecovers, muffler, wheels, gauges, and one of the exhaust manifolds. The frame and engine go together. It ran when I bought it, but poorly. None of the repairs required opening the engine or replacing any major mechanical systems.
My '77 550K was an original survivor combo. When I bought it had been sitting since 1981 or 1982 and still had the tires from the showroom. When I changed them the tubes had 1977 printed on them. The seat, tins, exhaust system, gauges etc all original to the bike. Hell, I didn't even bother to replace the brake shoes/pads, points, and drive chain when I got it back on the road. The only unoriginal cosmetic part on it was the suberbike bar and Randakk's grips. And I kept the original bars in case a future owner wanted them. Getting it running was a case of new battery and plugs, a good carb cleaning, and replacement of fuel lines and the tank petcock. I don't think I even replaced the air filter since it was nice and clean. The tool kit was under the seat and looked like it had never even been opened.