46mm or 42mm
aluminum or titanium case

44mm or 40mm
aluminum case

Wide-angle Always-On Retina display
Up to 2000 nits

Up to 40% brighter when viewed at an angle

LTPO OLED Retina display

Up to 1000 nits

ECG app

High and low
heart rate notifications

Irregular rhythm
notifications

Low cardio fitness
notifications

High and low
heart rate notifications

Irregular rhythm
notifications

Low cardio fitness
notifications

Sleep tracking

Sleep apnea notifications

Sleep tracking

Vitals app featuring heart rate, respiratory rate, wrist temperature, and sleep duration

Vitals app featuring heart rate, respiratory rate, and sleep duration