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Apple Watch Series 6 vs 4 (2021): How Does The New Apple Watch Compare?

Apple’s flagship wearable has been putting a premium on health and fitness features over the years. With the release of the Apple Watch Series 6, the world’s most popular smartwatch continues in the same direction. While the upgrades are incremental and its design remains largely unchanged, the refinements should prove a hit especially to those long clamoring for the new health functionalities. But how does it stack up against the critic’s favorite, the Apple Watch Series 4?

Apple Watch Series 6 vs 4 Comparison Chart

ModelApple Watch Series 6Apple Watch Series 4
Amazon product
PriceCheck Price at AmazonCheck Price at Amazon
Sizes40mm, 44mm40mm, 44mm
DisplayRetina OLEDRetina OLED
Always-on DisplayYesNo
U1 Ultra Wideband SupportYesNo
Heart Rate MonitorYesYes
ECG MonitorYesYes
Blood Oxygen MonitoringYesNo
Sleep TrackerYesNo
Fall DetectionYesYes
Fitness TrackingYesYes
ConnectivityWiFi, Bluetooth 5.0, GPSWiFi, Bluetooth 5.0, GPS
Water ResistanceUp to 50 metersUp to 50 meters
SoftwarewatchOS 7watchOS 7
Battery LifeUp to 18 hoursUp to 18 hours
Release Date20202018

Design and Hardware

The Apple Watch Series 6’s design remains largely the same except for some upgraded hardware and a new set of sensors.

The Apple Watch 6 (left) comes in new, vibrant color finishes compared to the Apple Watch 4 (right).

With the Apple Watch Series 4, the Cupertino-based tech giant released its largest display (1.78 inches for the 44mm model) while also drastically minimizing the bezels. The Apple Watch Series 6 follows suit, offering large displays both for its 40mm and 44mm models.

Design-wise, things remain largely unchanged. Indeed, while rumors abounded that the Apple Watch 6 would feature a circular screen similar to traditional analog watches, Apple knows if it ain’t broke, don’t fix it. Moreover, the Apple Watch’s rectangular form and rounded corners are already emblematic of the device. It’s so iconic that even other watches have emulated it.

Hardware is mostly the same, too. Since Series 4, Apple’s flagship wearables sport a digital crown with haptic feedback. Moreover, you can still choose from the same construction materials: aluminum, titanium, and stainless steel. The Apple Watch 6, however, comes with plethora of color finishes that veer from the neutral tones the watch has been known for. Both the Watch 4 and Watch 6 are waterproof up to 50 meters.

The big differences, however, are inside the case. The Apple Watch 6 comes with an upgraded 32GB of storage and a U1 chip for ultra wideband support. Apple introduced the latter feature in the iPhone 11 previously, and could be used for enhanced spatial awareness. Lastly, the introduction of a blood oxygen monitoring in the app means you get an all new set of sensors incorporated in the Apple Watch 6’s crystal back.

Health Features

Just like the Apple Watch 4, the Watch 6 is packed with health features. However, it introduces two new capabilities — sleep tracking and SpO2 monitoring. 

Here’s a closer look at the new Apple Watch Series 6 sensors for blood oxygen monitoring.

The Apple Watch Series 4 is already packed with several health features. In fact, the model was the first direct-to-consumer product allowing customers to take an electrocardiogram (ECG) test. Then, there’s the heart rate monitor, fall detection, and Medical ID features that went along with it. It’s truly a beast of a device.

With the Apple Watch Series 6, you’re not getting a revolutionary wearable. Instead, Apple is building on its predecessors’ success, refining existing features or introducing new ones. The Noise app, for instance, now has expanded functions that include managing listening volume levels.

In the case of new tech, you’ll finally get the rumored blood oxygen monitoring app. It’s a feature that’s already becoming a standard across several other smartwatches. And as mentioned in the hardware, the Spo2 monitoring comes with a new set of sensors made of a cluster of infrared LED lights. Apple Watch 6 is also capable of automatically detecting if your washing your hands and ensure you do so for 20 seconds. It’s a nifty feature that should find great use in today’s new normal.

Thanks to the new watchOS 7, the Apple Watch 6 will also include a native sleep tracking application. Simply called Sleep, the new app should help track sleep trends and provide users practical insight to establish a more regular bed routine. In addition, the feature comes with Sleep mode that enables the Do Not Disturb mode of the watch to help you finally nod off.

Fitness Features

The latest Apple Watch adds new workout profiles for tracking. 

Alongside the Apple Watch Series 6 and watchOS 7, Apple also launched Apple+ Fitness.

The Apple Watch Series 4 boasts a range of fitness features that has really helped define the wearable. With each successive watchOS update, the device gains access to even more capabilities. This includes automatic workout detection and long-term trends for daily routines. Both features are also on top of the handful of workout profiles you can already manually track.

On the Apple Watch Series 6, you’re getting some improvements on existing features as well. Unlike the Watch 4’s barometric altimeter, the Watch 6 now comes with an always-on altimeter capable of tracking elevations changes in real time. Apple claims it’s also more precise. Plus, the brighter display should make it easier to read metrics even under bright light conditions, perfect for a range of outdoor activities.

The rest of the updates, however, come with the upgrade to watchOS 7. Core and strength training, dance, and post-workout cooldown activities are now tracked by the Apple Watch 6. You can also share your activity metrics with friends if you’d like a dose of competition—and motivation.

But alongside the release of the device and OS, Apple also announced the launch of its subscription-based virtual workouts. Aptly called Apple Fitness+, the service is bound to rival existing programs offered by the likes of Fitbit and Peleton.

Battery Life and Other Features

The Apple Watch Series 6 still has the same battery life as the Watch 4.

With watchOS 7, you get new watch faces as well as access to Family Setup.

While most were hopeful the new Apple watch would bring improved battery life, the performance of the Watch 6 is still the same as the Watch 4. You get about 18 hours of power that should get you through the day. However, this is still quite dependent on usage. With always-on display and always-on altimeter options, the advertised battery life isn’t always going to be a reality. Compared with other smartwatches, the Apple Watch 4 and 6 are definitely on the modest side of battery life.

As expected, the new watchOS 7 will come along with new watch faces and complications, including multiple variations for a single app. Again, all these design elements are customizable. In fact, if you’re feeling generous you can share links to the custom watch faces you make to family and friends.

Apple’s family sharing has also found itself into the wearable. Called Family Setup, the feature allows even non-iPhone users to make the most out of the Apple Watch 6. A single iPhone is still required to pair with, but it does expand the market for wearable tech to more people in your household. Parents, in particular, will probably like the feature since as it affords control over who their children add as contacts or what apps they download.


The incremental upgrades on the Apple Watch Series 6 make it a more complete wearable compared with the Apple Watch Series 4.

Apple Watch Series 6

The smartwatch with more complete health and fitness features

Apple Watch Series 4

Still a solid device that offers capable health and fitness tracking

With its big display and the debut of ECG, the Apple Watch Series 4 pioneered a lot of firsts for Apple’s wearable. To this day, it remains an excitingly capable and robust device. It’s still a great entry-level to Apple wearables, combining smart features with a plethora of health and fitness tools. But it’s probably going to get less attention with Apple’s release of the Watch SE.

The Apple Watch Series 6, on the other hand, is all about refining an existing technology instead of actually revolutionizing it. As promising as a new design or improved battery life is, most of the latest wearable’s updates are actually incremental. However, the Watch 6 should prove to be a hit for users long clamoring for SpO2 monitoring and a native sleep App. Plus, watchOS 7 looks great. If anything, these little upgrades make the latest Apple watch the company’s most complete wearable.


📌  What are the new activities tracked by the Apple Watch 6?

The Apple Watch 6 now includes profiles for Dance, Core Training, Fucntional Strength Training, and Cooldown.

📌  How many languages can Siri translate on the Apple Watch?

Siri can translate up to 10 languages on the Apple Watch. This includes spoken translations, too.

📌  What’s the difference between the Apple Watch Series 6 from the Apple Watch Series 4.

Although they share the same form, design, and size, the Apple Watch 6 boasts blood oxygen monitoring and sleep tracking not available on the Watch 4. Moreover, the Watch 4 features an always-on altimeter and a brighter Retina OLED display.

📌  Does the Apple Watch 4 come in a GPS-only model?

The Apple Watch 4 is available in both GPS and GPS + Cellular models.

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Mari Bassig

Senior Editor, writer and researcher passionate about gadgets, social media, and music.