The Galaxy Note20 Ultra 5G has a 4,500mAh battery while the Galaxy Note10+.has a smaller 4,300mAh battery. Despite this larger battery, the Galaxy Note20 Ultra 5G is able to charge a lot faster with these new charging techniques.
Using the GRL-C2 USB PD Tester and GRL-PSP Power Analyzer software from Granite River Labs, we can compare how quickly the Galaxy Note20 Ultra 5G and Galaxy Note10+ charge with the GRL-C2 USB PD Tester emulating the Samsung 25W PD 3.0 PPS Type-C Charger that comes with the phones.
The Galaxy Note20 Ultra 5G takes much better advantage of the higher power capacity of the charger, and utilizes 22.5W to achieve fast charging for much longer than the Galaxy Note10+, which only achieves 22.5W briefly at the start of charging. However, to avoid the phone getting too hot while charging so quickly, Samsung periodically reduces the power to about 8W during cool down stages, keeping the max temperature of the phone below 40 degrees C. By contrast, the Galaxy Note10+ is much less aggressive and charges at about 15W for 6-7 minutes, and then drops down to under 6W for the rest of the charging cycle to 100% battery.
We can see that up until 80% battery, the Galaxy Note20 Ultra 5G uses USB PD PPS technology where the phone frequently tells the charger how much USB VBUS voltage is required, allowing VBUS voltage to vary around 9V. After 80% battery, the Galaxy Note20 Ultra 5G stops using USB PD PPS technology and the VBUS voltage becomes fixed at 9V.