I have ridden in both and to me, the logistics of Tevis being a point to point makes Tevis the harder ride (not a harder trail). I really didn't have crew at OD but it looked like there was crewing allowed at most of the vet checks where there is only crewing allowed at only three checks on Tevis. The last place you see your crew on the Tevis is 65 miles. I think the stress of trying to co ordinate getting a good stall at the Gold Country fairgrounds, moving up to Robie Park for the start a day before the ride, lining up crew to move your rig back to Foresthill/Auburn AND make it to Robinsons in time to crew makes Tevis more difficult.
As far as the trail itself....I think it is like comparing apples to oranges - both are fruit and both are sweet but they definitely have a different flavor. Depending on which taste you like (or dislike) makes you favor one over the other. As far as the two rides, they both are on beautiful trail and both present challenges that make you feel that the competition is with the trail not your fellow riders. Depending on the weather, the kind of day you are having (read LUCK), etc. one would seem more difficult than the other. I think the course for both is probably equivilent in as far as difficulty and challenges BUT the challenge and difficulty is different for both.
