While the non-Ultra phones within the Samsung Galaxy S25 series didn't see many hardware upgrades, the Ultra variant has many subtle changes. The slimmer bezels than the predecessor is one such example. This change may not be noticeable at first glance, but as Ice Universe has shown, a close-up comparison does make the thinner bezels of the S25 Ultra quite obvious.
The close-up shot showcased by Ice Universe also hints that Samsung has made quite an effort to increase the size of the display while lowering the phone's footprint. Samsung likely has not talked about the technological advancements it made for this during the Galaxy Unpacked event because the difference seems very negligible when viewed from a normal distance.
To fill you in, the Samsung Galaxy S25 Ultra sports Samsung's "hybrid oxide and polycrystalline silicon 3.0" tech. This is the company's version of LTPO. It offers improvements to the touch sample rate and efficiency compared to the predecessor, and it's also thought to be the tech that allowed the reduction of bezel size.
It's also worth noting that even a reduction of 0.1 mm increases production costs, and there's a lot of engineering effort behind it. Now, although the slightly larger screen may not be noticeable, the rounded corners and smaller footprint will make the Galaxy S25 Ultra comfortable to hold (pre-order on Amazon and get a $200 free gift card).