It seems Samsung equipped some of its Galaxy Note20 Ultra and Galaxy Note20 units with copper-enveloped vapor chamber cooling and others with layered graphite thermal pads. This was discovered by iFixit during their teardown of the Galaxy Note20 duo. Both of their Snapdragon 865+ units come with graphite thermal pads (seen below) for heat dissipation, however they've found evidence in this teardown video of a Galaxy Note20 Ultra with a vapor chamber cooling solution. And it doesn't appear to be an Exynos vs Snapdragon issue, as Zack Nelson from JerryRigEverything states his Exynos...
Source: https://www.gsmarena.com/some_galaxy_note20s_have_vapor_chamber_cooling_others_use_graphite_-news-44905.php
