Have you done an Enduro event? Then you know what it is about! If not, then here is a summary: riders get timed only on certain sections, which make a very social event, especially at the refreshment station where they re-group. The atmosphere is relaxed with no rush anywhere, except when you gun it between check points!
Total distance of riding not so relevant as riders ride to special stages in their own time and the timed stages are more like downhill racing, although all type of riders can attempt it. Protective gear recommended.