One gives an interesting historical perspective. The other talks more about 3/4-ton vs 1-ton, which is really just a rating difference to be under Class 2b 10k lb limit for classification. The biggest exception to that rule is the Ram 2500's 4-link rear suspension.
rvlifemag.com

Load capacity of 3/4 ton trucks | RV Lifestyle Magazine

Pickup Trucks 101: How Do SRW 2500s and 3500s Differ? | PickupTrucks.com
Trying to decide between a 2500 and 3500 pickup? Here's help.
news.pickuptrucks.com