What does it sound like when you knock on it? Does it sound very hollow? You should be able to tell the difference between wood panelling (which for internal use is often quite thin) applied to a framework, or applied to gyprock. If there is a power point in that wall, take it off, and see if there is any thickness of gyprock / plaster - it will be obvious if it exists.
Also, if you can see patterns of nails or screws about 450mm or 600mm apart as you work your way across the wall, this may indicate that it is actually fixed directly to the stud work. Studs are either of these distances apart (and have been for some time) and I doubt you would nail panelling to plaster or gyprock anyway. If there's no visible fixings, its a good indication the panelling is glued, however it could also be glued to the stud work but that's not highly likely.
The best test would be to take a power point off if one exists. Then it's reversible, and you won't have to go drilling holes into it.