Not much if you consider that are quite structured, and half the price :)
28 liters / 680gr / $150
Unlucky they don't have > 28 liters models, so we have to compare to the 40 liters ones.
https://www.hyperlitemountaingear.com/products/2400-junction
40 litters / 878gr / $349
These are full water proof? I read: "Pair with our Stuff Sacks for a buttoned up, nearly waterproof kit."