Withings devices
PhonesVS currently lists 2 Withings devices: 2 in smartwatches. Each page shows the specification sheet, and you can compare any two Withings models or put one against a competitor. Recently covered: Withings ScanWatch Light, Withings ScanWatch 2.
Smartwatches 2

Withings ScanWatch Light
The cheaper, slimmer ScanWatch: analog hands, a small OLED display, sleep and heart rate tracking and up to 30 days of battery, but no ECG, SpO2 or temperature sensor.

Withings ScanWatch 2
A hybrid analog watch with a small OLED display, ECG, SpO2 and 24/7 skin temperature tracking, a sapphire glass case and a battery Withings rates at around 30 days.