+ Better battery
+Better Camera
+ New button
+ Stronger screen
+ Better CPU
+Better GPU
So is it worth buying? Yes, a big yes if you have an older model and NOT the 15 pro, the improvements in this model are basically the same as the 15 over the 14, So if you have a iPhone 13 or older I would say its worth it big time, but not if you have a 15.
I also will say the same for Samsung, I own a s24 ultra and use it as my main phone and its improvements over the 23 ultra is basically the same every year just like apple.