Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Garmin - Lily 2 | Oura - Ring 4 |
|---|---|---|
| Battery life | 5 days | 8 days |
| Sport modes | 20 | 40 |
| Water resistance | 5 ATM | 10 ATM |
Between the Lily 2 and Ring 4, the Lily 2 comes out ahead in several specs, while the Ring 4 wins on battery life / sport modes. Overall, the Lily 2 scores 64.2 and the Ring 4 scores 63.8 on our Mars Score.
Which should you buy?
These two are nearly even on the Mars Score (64.2 vs 63.8). The decision is not about overall quality — both clear the bar — it is about which specific trade-offs fit your use.
The Lily 2 does not pull ahead on any single popular-comparison spec — its strengths sit in the spec-table groups rather than the headline advantages.
Pick the Ring 4 if you care most about battery life / sport modes. Its strongest claims are battery life, sport modes, water resistance. The single most decisive one: Battery life — 60.00% more. 8 days vs 5 days.
Both ship with comparable gps, spo2, so those specs do not 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 says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: Garmin - Lily 2 or Oura - Ring 4?
Garmin - Lily 2 leads the current Mars Score by 0.4 points.The more useful decision is the trade-off behind that result: compare battery life against the way you will actually use the product.
Choose Garmin - Lily 2 if…
Garmin - Lily 2 does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
Choose Oura - Ring 4 if…
Oura - Ring 4 has the measurable edge on battery days, sport modes, water resistance atm.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why Garmin - Lily 2 wins
- No decisive advantages.
Why Oura - Ring 4 wins
- ▲Battery life — 60.00% more. 8 days vs 5 days.
- ▲Sport modes — 20.00 more. 40 vs 20.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
Spec comparison
Fitness
| Spec | Garmin - Lily 2 | Oura - Ring 4 |
|---|---|---|
| GPS | false | false |
| Heart rate | true | true |
| SpO2 | true | true |
| Sleep tracking | true | true |
| Sport modes | 20 | 40lead |
Battery
| Spec | Garmin - Lily 2 | Oura - Ring 4 |
|---|---|---|
| Battery lifeⓘ | 5 days | 8 dayslead |
| Water resistanceⓘ | 5 ATM | 10 ATMlead |
Design
| Spec | Garmin - Lily 2 | Oura - Ring 4 |
|---|---|---|
| Display size | 1.0 "lead | 0 " |
| Weight | 21 g | 3.3 glead |