Why are chin-ups harder than pull-ups?

When looking at world records pull ups always have better numbers than chin ups. For example the record is 707 pull ups in 30 minutes versus 600 chin ups in 30 minutes and the weighted pull up is heavier than the weighted chin up, the pull up world record is 104.55 kg versus the chin up world record being 92.25 kg.

Also the most pull ups done in 24 hours by a person is 7345 versus only 5050 chin ups.

There’s also many videos of people doing 50 or more clean pull ups in one set and one guy even did 105 strict military pull ups in one go, but barely any video of people managing to get to at least 30 chin ups in a row.

I myself can pull up 33 times in a row with clean form and way more than that if I cheat…getting chin ups is way harder.

The movement of chin ups feels mechanical and robotic and I can’t do more than 12 with good form. I don’t know, it just feels like my bones are not made for this movement and I feel it is hard to even begin the movement, the only thing changing is grip position but the movement feels completely different.. It may look the same motion but it doesn’t feel like that.

A pull up just feel like one big pull, al at once but a chin up feels like a 4 sequence movement forced into one… It’s not just a pull it’s a shoulder shrug, a bicep curl, a lat pull and then a chest pull.

It is clear however that to bodybuilders and beginners chin ups are easier, but when it comes to people who specialize in pulling motions pull ups are easier as evidently suggested by the fact that no chin up specialist ever beat a pull up specialist neither in weight or reps.

So I wanna know the difference between a beginner/bodybuilder and someone who specializes in tractioning motions aka pull ups/chin ups, why are pull ups easier for elites and chin ups easier for beginners and bodybuilders?

I do not believe it is personal structural differences, because if some people were actually born to be better at chin ups than others, then chin up specialists would not be so far behind to pull up specialists.

And why is simply rotating the forearm into supinated position making everything so hard? Now that I think about that…almost every exercise ever invented is easier with a pronated grip. Bench, standing press, front squats, back squats… Deadlifts…and god knows what would happen if someone tried to clean and press with a supinated grip.

Probably the only exception are dumbell curls, they seem easier with a supinated grip, but barbell curls also feel more natural with a pronated curl than supinated barbell curls. But there’s also a lot of people who can curl way more weight with neutral grips, so even that is a weak one as an exception.

If the link does not work, here’s the normal version

http://www.recordholders.org/en/list/chinups.html