Not only will those two likely fall into more hands than the Ultra, but they are also receiving a significant boost in the main camera sensor, although you couldn't tell by the specs sheet, as it is still a 12MP shooter that is listed there, just like on their predecessors of the S10 series... and the S9 series... and, you catch the drift.
The S20 and S20+, however, should come with a new 12MP sensors that sport huge 1.8 micron pixels, much larger than the 0.8 micron dots of the 108MP sensor reserved for the Ultra, or the 1.4 micron pixels of the S10 series.
Samsung still managed to set the Ultra apart by introducing the Nonacell technology, combining nine adjacent pixels into one to reach the whopping 2.4 micron virtual pixel size on its most expensive S-line phone to date but the S20 pixels are big with no virtual shenanigans.
Does it matter? Yes, it does, as a larger pixel is simply a larger bucket that can collect more light than a smaller one, thus giving the phones theoretical advantage in low-light shots. What's lower lighty than a pitch black yard that needs Samsung's Night Mode fired up to display anything at all in the viewfinder?
Well, that's exactly the setup used in the first leaked samples of a low-light comparison between the S20 and S10 cameras taken with Night Mode. It's much easier to discern objects on the sample taken with the S20, but then again its night shot algorithm may be different, we'll take it for a longer spin today and relay everything we find.