iOptron Tri Pier vs 2" Tripod

The iOptron Tri Pier weighs 25.8 lbs and has a max payload of 220 lbs. The 2" Steel tripod weighs 17.1 lbs and has a max payload of 300 lbs.

I'm just curious why there's such a big difference in payloads.

Also, is the Tri Pier that much more stable that it would cost twice as much as the tripod? It also seems like the 3" range on leg adjustment might be a bit of a limit too. So what's the main advantage of the Tri Pier?

Thanks for any insight,
Jeff