Apple - Watch Ultra 2 vs Xiaomi - Watch S4

The Watch S4 edges ahead on the Mars Score (60.5 vs 63.9), but the 3.4-point gap is small enough that the right pick comes down to which spec advantages matter to you.

Pick the Watch Ultra 2 if the display is what you stare at all day — refresh rate, brightness, or sharpness is where the difference will be most visible. The biggest gaps in its favor are peak brightness, display size, water resistance.

Pick the Watch S4 if your top frustration with your current device is running out of charge before the day ends — endurance is the lead spec here. Its strongest claims are battery life, weight.

Both ship with comparable ecg, cellular, spo2, so those specs don't separate the two — focus on the differences below.

Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity tells you both are well-rounded; the differences are about trade-offs, not quality.