My sense is watches actually have much finer granularity data collection, because of power capacity. The Oura collects data during wearer sleep about once a min

My sense is watches actually have much finer granularity data collection, because of power capacity. The Oura collects data during wearer sleep about once a minute, while Samsung watch at least collects every 5-10 seconds. But in terms of sensor modalities they are the same. Personally I much prefer rings to watches, that's all.