Yes, it's just local dimming. But also, putting an array of x LEDs on a 65-inch device isn't the same as cramming the same amount of LEDs into a 14-inch screen.
Scaling them down is hard, which is also why we don't have micro-LED yet.
I guess Apple wants the advantage of making it clear that it's a whole new thing every year, but an iPhone 34 Pro Max is just ridiculous.
The Mac solved this long ago. You just get the new iPhone. You decide on a level: the iPhone, or the iPhone Pro. And then you decide on a screen size: the 5-inch iPhone Pro, or the 6-inch iPhone Pro.
Then, where it matters (support articles), you add "(late 2020)".
Heck, it's what car manufacturers also do. You have a model year. Done.
Again, Apple doesn't want to do this because it doesn't have the same wow effect. But "iPhone 11 Pro Max" is not a great, sustainable product name. Is the next one the "iPhone 11S Pro Max"? The "iPhone 12 Pro Max"? How much better is 12 than 11, really? How much better is 22 than 21?