Last week at Mobile World Congress, Samsung unveiled its 2018 flagship phones, the Galaxy S9 and S9+. We've already looked at how they stack up against Apple's latest iPhones, but how much of an improvement are they over Samsung's own previous models? If you're lugging around a 2017 Galaxy and wondering if it's worth the upgrade, New Atlas compares the specs and features of the Samsung Galaxy S8, S8+, S9 and S9+.
Size

Both Galaxy S9 models are slightly shorter and narrower than their 2017 counterparts, but have gotten a little thicker in the process.
Weight

At the same time, the newer models have also put on a little weight. That said, you're probably not going to notice the difference unless you were holding both at the same time.
Colors

Black, blue and gray options are sticking around across generations, but Samsung has dropped gold and silver for a pinch of purple.
Build

All four of these Galaxy phones are encased in glass front and back and ringed with aluminum.
Water resistance

Samsung has been building phones with a decent water resistance rating for years now, so of course the S9 line is no different. IP68 means that the devices are dust-tight and can withstand being submerged in up to 1.5 m (4.9 ft) of water for up to 30 minutes. We'd recommend not testing that out yourself, but there's peace of mind in knowing that these phones will bounce back from any accidental spills, splashes or dunks.
Display size

The display sizes remain the same from the S8 to S9, and S8+ to S9+.
Screen-to-body ratio

This can be a bit of a murky metric but, despite some minor size changes, the screens take up roughly the same amount of real estate on the front as last year.
Display resolution

Again, the resolution of each phone's screen remains unchanged between 2017 and 2018.
Display type

Samsung is sticking to its so-called Super AMOLED screens, which should give them brighter colors and better contrast than the IPS LCD screens on the iPhone 8 and 8 Plus. That said, colors may look a little less natural than those alternatives.
Biometrics

On paper, the new generation phones have the same biometric sensors as last time, including fingerprints, facial recognition and iris scans. The difference is that the S9 and S9+ can combine these for extra security, so the phone might not unlock unless it detects both your face and eyes at the same time. The fingerprint scanner on the back of the phone has moved too, now residing underneath the camera lens instead of beside it.
Processor

For users in the US and China, the brains of the new phones are the latest Octacore chipsets from Qualcomm, the Snapdragon 845. For most of the rest of the world, you get a comparable Exynos 9810 Octacore processor instead. In practical terms though, the difference is pretty negligible.
RAM

The S9 keeps with the 4 GB baseline of RAM that most flagship phones have stuck to for the last few years, while the S9+ boosts that to 6 GB.
Onboard storage

Where the Galaxy S8 phones only offered a single option of 64 GB of built-in storage, the S9 and S9+ can be kitted out with twice or four times that amount.
MicroSD

The storage space inside all four of these Galaxies can be expanded by way of the MicroSD card slot. The upper limit for the S8 and S8+ is an extra 256 GB, while the S9 and S9+ can accommodate cards up to a mammoth 400 GB.
Battery

Battery capacity hasn't changed either. The base model still sports a 3,000-mAh battery, while the plus gets 3,500 mAh. If those numbers don't mean anything to you, all four phones will probably need a charge once a day with moderate use.
Ports

Unlike many competitors, Samsung has so far resisted the siren song of killing off the 3.5 mm headphone jack. You can still use Bluetooth headphones of course, but we appreciate being given the choice. The Galaxies charge via USB Type-C.
Fast charging

The option for fast charging is available right out of the box. It's a handy feature for when you need a quick top-up before heading out.
Wireless charging

All four Galaxies can also be wirelessly charged, although that requires the separate purchase of a wireless charging pad. It's nice to have the option, but for now we're still questioning how useful it really is.
Front camera

The front-facing cameras haven't changed, but with a resolution of 8 megapixels and an aperture of f/1.7, you'll get decent enough selfies out of them.
Main camera

The primary camera was one of the key areas for improvement between the S8 and S9 generations. The Galaxy S9 has a dual aperture, allowing the camera to automatically switch between f/1.5 for better low-light shots, and f/2.4 for more detail under normal lighting.
Meanwhile, the S9+ has two cameras – a wide-angle lens with the same specs as on the S9, and a 12-megapixel telephoto lens with an aperture of f/2.4.
Photo/video modes

With those camera upgrades come some impressive new video and photo modes. All four phones can shoot with High Dynamic Range (HDR), and in slow motion at 240 frames per second – although the new models can shoot slow-mo at Full HD (1080p), rather than just the 720p resolution of the S8s.
The really impressive mode on the S9 and S9+ is Super Slow-mo, which can capture video at 960 frames per second in 720p – an achievement first seen on the Sony Xperia XZ Premium.
For the emoji-inclined, there's also a new system that's clearly inspired by the iPhone X's Animoji mode. S9 and S9+ users can scan their faces to create animated "AR Emoji" of themselves to send via messages as GIFs and still images.
Operating system

The Galaxy S9 and S9+ come preloaded with Android 8 out of the box, while the older models can get it through a software update.
Assistant

Samsung is pushing its voice assistant Bixby on all of its phones.
Payments

All four phones are also equipped with Samsung's own mobile payment system.
Release

The Galaxy S8 and S8+ were released in April last year, while the S9 and S9+ are due to launch on March 16.
Price (US$)

The impending release of the new models means that last year's have seen a price drop recently. The S9 and S9+ seem to start at the same launch prices as the S8 and S8+ did.