So for bright light shooting, the Samsung should have a resolution advantage assuming that the lenses are of equal high quality, and diffraction isn't limiting the actual perceived sharpness from images. Given my personal experience with m43 photography where we get into diffraction limits at F8 - F11 with a much larger per pixel size on a m43 sensor, I really doubt that for pragmatic reasons that we will see huge differences in detail going to 108mp on a Galaxy Note 20 Ultra over an iPhone or most other phones on the market for that matter from an ability to resolve 108mp perspective. Most detail improvements in bright light on phones will more likely comes from pixel shifting techniques and computational photography in the long haul where you don't have to worry about diffraction effects but you do have to worry about motion blur IMHO.
For low light, we are comparing 1.4 μm per pixel for the iPhone VS 0.8 μm for the Note 20 Ultra.
Theoretically the iPhone's larger per pixel size **should** allow for better low light before we factor in computational processing , pixel shifting etc...
Having said that, downsampling from a higher megapixel to a lower megapixel does result in improved perceived noise performance.
I'm interested to see how the two cameras compared downsized to the same 4k resolution as my 65" Frame TV. Or downsized to my original Canon 5d (I still have a 20X30 print at home from that!).