In reply to waterfall:
> which one did you each run, [...] What is the difference between each?
I started with the CCC in 2017, did the (old) TDS in 2018 and did the UTMB proper in 2021.
UTMB is the umbrella term for the festival of races but also the original Ultra Trail du Mont Blanc headline race which starts on Friday evening. 171km loop starting and finishing in Chamonix in a counter clockwise loop via Courmayeur and Champex in Italy and Switzerland taking in 10,000m if elevation.
Kilian Jornet set a course record last year under 20 hours but the official cutoff in 46. Because of the start time even the pros have to run a full night, but most mortals run through two consecutive nights so it's a bit of a mental challenge.
The TDS starts in Courmayeur and finishes in Chamonix via Col de Petiti Saint Bernard, Bourg St Maurice, Beaufort and finishes in Chamonix. When I did it, it was only 120-odd km but more technical and bit more rugged than UTMB and more vert per km. They've since increased the distance to around 150km and many argue it's now harder than the UTMB. It started midnight on Tuesday.
CCC starts in Courmayeur and after a small variation basically is the last 100km of the UTMB. Starts tomorrow morning at 9am ish
OCC is 50km from Orcieres to Chamonix. I think MCC is reserved for locals and volunteers and YCC is a specific youngsters race.
PTL is more mountain marathon, orienteering style in pairs or threes for 300km over most of the course of the week.
All of the above from memory so may have mistakes.
The whole thing is a massive circus that really polarises runners. You can only enter (by lottery) after having amassed enough points acquired by running accredited races (which organisers have to pay to be accredited for) so naturally many people don't take a favourable view. In fact the UTMB organisation have recently gone a bit down the ironman triathlon route in the way they're running a series of world events which I don't think anyone is massively in favour of.
However as an ultra runner there's nothing like it. Literally thousands of spectators and amazing organisation. The atmosphere is incredible and all three races were experiences that were worth the effort of getting there for me.