This video compares the Performance Mode and Quality Mode of Metal Gear Solid Delta running on the PlayStation 5 Pro.
For the uninformed, the Performance Mode features a 1080p native resolution that upscale to 4K, while the Quality Mode features a 1440p native resolution that upscale to 4K.
Both modes target a maximum of 60 frames per second.
You can check out the comparison below:
As you can see, the difference between the two is quite small. If you look close enough, some textures (like the text carved onto the knife) appear sharper in Quality Mode.
On the other hand, Quality Mode does drop more frames, even during a cutscene, when compared to Performance.