The holidays are a good time to buy a smartwatch. If you're thinking about upgrading your current Apple Watch or buying an Apple wearable for the first time, you may be considering the new Apple Watch Series 10. But you might wonder how it stacks up against last year's Series 9, which can often be found at a much lower price. The Series 10 starts at $400 in the US, just like the Series 9 did at launch (you can find pricing for the UK and Australia in the chart below). There are some key differences between these wearables. Namely, the Series 10 offers a bigger screen and larger case sizes, plus it has a new voice isolation feature and can play music aloud on the speaker. Keep reading for an even closer look at how the Series 9 and 10 compare.Buy Apple Watch Series 10Buy Apple Watch Series 9 Watch this: Apple Watch Series 10 vs. Series 9: Spec Breakdown 05:34 Apple Watch Series 10 gets a bigger and brighter screen Hello, Apple Watch Series 10. James Martin/CNETThe Series 10 has the biggest screen of any Apple Watch yet. It's available in two new sizes; a 46-millimeter and a 42-millimeter option. That 46-millimeter option is even slightly larger than the Apple Watch Ultra. The Series 9, on the other hand, comes in a 45-millimeter and a 41-millimeter option.Apple says that a bigger Series 10 display gives you up to 30% more screen area compared to the Series 4, 5 and 6, and up to 9% more screen area compared to the Series 7, 8 and 9. In everyday use, that means you can have an extra line of text on your watch, or up your font size without losing content. Buttons for things like the Calculator app and typing in your passcode are bigger, too. The Apple Watch Series 9 (left) is slightly smaller than the new Series 10. Lisa Eadicicco/CNETThe Series 10 is also brighter. Both the Series 9 and 10 have a maximum brightness of 2,000 nits, but the Series 10's wide-angle OLED makes the screen 40% brighter when viewed at an angle. While typing her Apple Watch Series 10 review, my colleague, Lexy Savvides, wore the Series 9 and 10 on the same wrist. When she glanced down to check the time at an angle, she found that the Series 10 looked slightly brighter.The Series 10 also has an LTPO 3 display that can get down to a 1Hz refresh rate, allowing a ticking second hand to appear on the always-on display. Not only is LTPO 3 not offered on the Series 9, but it's rare to see on smartwatches, in general. It's more commonly found on premium smartphones like the iPhone 15 Pro Max and the Galaxy S24 Ultra. In her Series 10 review, Lexy raves about the ability to see that ticking second hand without having to wake her watch screen up.Apple Watch Series 10 is thinner and lighterThe Series 10 is also the thinnest Apple Watch ever. It's 9.7 millimeters thick, while the Series 9 is 10.7 millimeters thick. That's about a 10% difference. The Apple Watch Series 10 (top) is 1 millimeter thinner than the Series 9. Lisa Eadicicco/CNETThe Series 10 comes in aluminum and titanium finishes, while the Series 9 is available in aluminum and stainless steel finishes. Both the aluminum and titanium Series 10 models are lighter than the equivalent Series 9 models.Yes, the Apple Watch Series 10 charges faster, but the battery life is the same The Series 10 charges faster than the Series 9, but the battery life is identical. Celso Bulgatti/CNETThe Series 10 offers faster charging than the Series 9. Apple claims that going from 0% to 80% takes around 30 minutes on the Series 10 and 45 minutes on the Series 9. In her Series 10 review, Lexy notes that she charged the watch from 7% to 84% in half an hour, so her test pretty much matched Apple's claim.Apple also says that the battery on both the Series 9 and 10 lasts up to 18 hours, or up to 36 hours in Low Power Mode. In her review, Lexy points out that it's unfortunate that the Series 10 doesn't offer a longer battery life than the Series 9, especially now that Apple is leaning more heavily into sleep-oriented features like sleep apnea detection (more on that below), and I agree.Apple Watch Series 10 has a stellar new voice isolation feature The Apple Watch Series 10 speaker lets you play music. James Martin/CNETThe Series 10 has a voice isolation feature not found on the Series 9. It's meant to reduce background noise as you take calls. So for her Series 10 review, Lexy put this feature to the test in a noisy scenario: a dragon dance at Lion Dance Me in San Francisco. Dragon dances happen during events like Lunar New Year celebrations and include drums that can be quite loud. Thanks to voice isolation, even when Lexy called our colleague,Lisa Eadicicco, from a dragon dance, they were both able to hear each other.The Series 10 also allows you to play music aloud on the speaker, while the Series 9 does not.New Apple Watch Series 10 water features The depth gauge on the Apple Watch Series 10 makes it ideal for snorkelers. Lisa Eadicicco/CNETBoth the Series 9 and 10 are water resistant and swim-proof, but the Series 10 has a depth gauge rated for 6 meters and a water temperature sensor not available on the Series 9. The Series 10 also has the Oceanic Plus app for snorkeling, while the Series 9 does not.Apple Watch Series 9 and 10 receive a new sleep apnea feature with WatchOS 11The Apple Watch Series 9, Series 10 and Ultra 2 have a new tool for detecting potential signs of sleep apnea. It uses the accelerometer, along with Apple's algorithms, to recognize possible breathing disturbances as you sleep. You can read more about how it works here. This sleep apnea feature comes with WatchOS 11, which ships on the Series 10 and is also available for the Series 9.Additionally, WatchOS 11 brings a new Vitals app that monitors important metrics as you sleep, like heart rate, respiratory rate and wrist temperature. The app will highlight these metrics if they're abnormal and notify you if you have two or more outliers.With WatchOS 11, both wearables also allow you to pause your rings to take an activity break. It's also worth noting that WatchOS 11 is available as an update for older Apple Watches dating back to the Series 6 and second-generation SE. You can now pause your rings on the Apple Watch Series 9 and 10 with WatchOS 11. Celso Bulgatti/CNETRead more: Best New WatchOS 11 Features You Need to Try On the Apple WatchBeyond the new tools that come to the Series 9 and 10 with WatchOS 11, these wearables share many of the same features you may already be familiar with, like high and low heart rate notifications, emergency SOS and fall and crash detection (see the chart below for more).Should you upgrade? The brand-new Apple Watch Series 10 is not a huge jump from last year's model. James Martin/CNETIn short, the Series 10 offers a bigger, brighter screen and larger case sizes, while being thinner and lighter than the Series 9. The Series 10 also has voice isolation and allows you to play music aloud on the speaker, unlike last year's model. If you're upgrading from the Series 9, these differences probably won't feel very stark. If you're currently using a Series 4, 5 or 6, they likely will. That bigger and brighter screen will be more noticeable, you'll gain access to new features and you'll get WatchOS updates for longer.For more on how the new Apple Watch Series 10 compares to last year's Series 9, check out the spec chart below.Apple Watch Series 10 vs. Apple Watch Series 9 Apple Watch Series 10 Apple Watch Series 9 Shape SquareSquareWatch size 42mm, 46mm41mm, 45mmMaterials, finishes Aluminum, titaniumAluminum, stainless steelDisplay size, resolution 42mm: 1.65-inch OLED 446 x 374 pixels; 46mm: 1.81-inch 496 x 416 pixels41mm: 1.61-inch, 430 x 352-pixel OLED; 45mm: 1.77-inch, 484 x 396-pixel OLEDDimensions 42mm: 42 x 36 x 9.7mm; 46mm: 46 x 39 x 9.7mm41mm: 35 x 41 x 10.7 mm; 45mm: 38 x 45 x 10.7 mmWeight 29.3g-41.7g depending on size, material and connectivity31.9g-51.5g depending on size, material and connectivityColors Aluminum: silver, rose gold, jet black; titanium: natural, gold, slateAluminum: midnight, starlight, silver, pink, Product Red; stainless steel: graphite, silver, gold; Hermes stainless steel: silver, space blackAlways On YesYesInterchangeable bands YesYesGPS YesYesAutomatic workout detection YesYesCompass YesYesAltimeter YesYesWater resistance 50m, IP6X dust resistance50m, IP6X dust resistanceCalls YesYesMicrophone YesYesSpeaker YesYesVoice assistant Yes (Siri, on-device)Yes (Siri, on-device)Mobile Payments Yes (Apple Pay)Yes (Apple Pay)Sleep tracking YesYesPeriod tracking YesYesSensors Accelerometer, altimeter, gyroscope, temperature sensor, compass, third-gen optical heart sensor, electrical heart sensor, ambient light sensor, depth gauge, water temperature sensorAccelerometer, altimeter, gyroscope, temperature sensor, compass, third-gen optical heart sensor, electrical heart sensor, ambient light sensorEmergency features Fall detection, crash detection, Emergency SOS, international emergency calling, noise monitoring, BacktrackFall detection, crash detection, Emergency SOS, international emergency calling, noise monitoring, BacktrackCompatibility iOS 18 and neweriOS 17 and newerSoftware (at launch) WatchOS 11WatchOS 10Processor Apple S10Apple S9Connectivity LTE and UMTS, Wi-Fi 4, Bluetooth 5.3, second-gen ultra widebandLTE and UMTS, Wi-Fi 4, Bluetooth 5.3, second-gen ultra widebandMemory and storage 64GB capacity64GB capacityCharging USB-C magnetic fast charging cableUSB-C magnetic fast chargingBattery life Up to 18 hours; up to 36 hours in low power modeUp to 18 hours; up to 36 hours in low power modeBattery capacity UnavailableUnavailableUS price 42mm: $399 (Wi-Fi); 42mm: $499 (cellular); 42mm: $699 (titanium); 46mm: $429 (Wi-Fi); 46mm: $529 (cellular); 46mm: $749 (titanium)41mm: from $399; 45mm: from $429UK price 42mm: 399 (Wi-Fi); 42mm: 499 (cellular); 42mm: 699 (titanium); 46mm: 429 (Wi-Fi); 46mm: 529 (cellular); 46mm: 749 (titanium)41mm: from 399; 45mm: from 429Australian price 42mm: AU$649 (Wi-Fi); 42mm: AU$809 (cellular); 42mm: AU$1,199 (titanium); 46mm: AU$699 (Wi-Fi/Bluetooth); 46mm: AU$859 (cellular); 46mm: AU$1,279 (titanium)41mm: from AU$649; 45mm: from AU$699