As I understand it, "Enduro" as an event is where you are timed for short sections of the route and have a time limit for the whole thing but your position in the results is dependent on your performance through the timed sections only. A bike developed for this kind of thing might be branded an "Enduro" bike.
Strathpuffer and other similar events are completely different - how many laps can you/your team complete in whatever time (24 hours for Strathpuffer). These would usually be ridden on a "hard tail" (i.e. bike with front suspension only). Downhill bikes are "full sus" (i.e. front and rear suspension).