Smartwatches and fitness trackers from Samsung, Ravoz and Endefo. See also Wearables.
Check compatibility before anything else. Some watches lose meaningful features when paired with a phone from a different manufacturer, and the limitation is rarely obvious on the box.
Battery life separates the categories more than features do. A full smartwatch runs a day or two; a fitness-focused band runs a week or more. If you want sleep tracking, a watch you charge nightly will not deliver it.
For swimming, look for 5ATM or higher rather than a generic "water resistant". And if health tracking is the point, check which sensors are actually present — heart rate is standard, blood oxygen and ECG are not.
