Survive Drops and Water Better
Apple says that they've improved the durability of the iPhone 11, which is great news if you drop your phone often. The iPhone 11 uses a new stronger glass, that Apple shows falling off all kinds of things in the promo video. It will be interesting to see how well this holds up in the real world, but it should help.
Additionally, it is now water-resistant for 30 minutes and up to 2 meters. This is double the depth of the iPhone XR. If you take your phone to the pool or beach, this is a nice upgrade.
The iPhone 11 Pro doubles this to 4-meters if you need even more protection from water.