Samsung's Galaxy S9 is officially here -- and maybe you like what you see? 

Maybe you're in the market for a new phone right now, in fact. But there are two versions to choose from: the Galaxy S9 and the Galaxy S9 Plus. 

Why would you pick one over the other? Let's discuss differences -- and afterwards, I'll describe what they have in common. 

Size

As you might expect, the Galaxy S9 Plus is larger than the vanilla Galaxy S9, which may make it a better pick if you want a bigger screen or have larger hands. While each screen has the same 2,960x1,440-pixel resolution, the S9 Plus screen is larger at 6.2 inches, compared to the 5.8-inch diagonal Galaxy S9.

And while both devices are the same thickness -- 8.5mm, or about a third of an inch -- the S9 Plus's body is larger too. It's 0.4 inches (about 10mm) taller and 0.2 inches (about 5mm) wider as well. 

Bigger doesn't necessarily mean better, of course. I prefer a smaller phone, and there's pixel density to consider, too -- since the Galaxy S9 crams more pixels into the same space, it's likely better for VR games where those pixels get blown up big by the Gear VR or Google Daydream View's magnifying lenses.

All of this was true of last year's Galaxy S8 and Galaxy S8 Plus, too -- unlike the Galaxy S7 and S7 Edge, where one had a curved screen and the other didn't. Things are more standardized now.

Camera

This is the big one. The Galaxy S9 Plus has two cameras on the back, and the regular Galaxy S9 doesn't.

While both phones have Samsung's fancy new 12-megapixel dual-aperture camera (which lets in more light by adjusting the size of the phone's iris, much like a DSLR), only the Galaxy S9 Plus has a second 12-megapixel camera with a 2x telephoto lens for zooming in closer to your subject.

It's a shame you can't have both cameras on the smaller phone -- Apple's iPhone X does.

Read more about the Galaxy S9's cameras here.

Samsung Galaxy Spec Showdown

	Samsung Galaxy S9	Samsung Galaxy S9 Plus	Samsung Galaxy S8	Samsung Galaxy S8 Plus	Samsung Galaxy Note 8
Display size, resolution	5.8-inch; 2,960x1,440 pixels	6.2-inch; 2,960x1,440 pixels	5.8-inch; 2,960x1,440 pixels	6.2-inch; 2,960x1,440 pixels	6.3-inch; 2,960x1,440 pixels
Pixel density	570ppi	529ppi	570ppi	529ppi	522ppi
Dimensions (Inches)	5.81x2.70x0.33 in	6.22x2.91x0.33 in	5.9x2.9x0.31 in	6.3x2.9x0.32 in	6.4x2.9x0.34 in
Dimensions (Millimeters)	147.7x68.7x8.5 mm	158.1x73.8x 8.5 mm	148.9x68.1x8mm	159.5x73.4x8.1 mm	162.5x74.8x8.6mm
Weight (Ounces, Grams)	5.75 oz; 163g	6.66 oz; 189g	5.5 oz; 155g	6.1 oz; 173g	6.9 oz, 195g
Mobile software	Android 8.0 Oreo	Android 8.0 Oreo	Android 7.0 Nougat	Android 7.0 Nougat	Android 7.1.1 Nougat
Camera	12-megapixel	Dual 12-megapixel	12-megapixel	12-megapixel	Dual 12-megapixel
Front-facing camera	8-megapixel	8-megapixel	8-megapixel	8-megapixel	8-megapixel
Video capture	4K	4K	4K	4K	4K
Processor	Octa-core Qualcomm Snapdragon 845 (2.8GHz+1.7GHz) or octa-core Samsung Exynos 9810	Octa-core Qualcomm Snapdragon 845 (2.8GHz+1.7GHz) or octa-core Samsung Exynos 9810	Octa-core Qualcomm Snapdragon 835 (2.35GHz+1.9GHz) or octa-core Samsung Exynos 8895	Octa-core Qualcomm Snapdragon 835 (2.35GHz+1.9GHz) or octa-core Samsung Exynos 8895	Octa-core Qualcomm Snapdragon 835 (2.35GHz+1.9GHz) or octa-core Samsung Exynos 8895
Storage	64GB, 128GB, 256GB	64GB, 128GB, 256GB	64GB	64GB	64GB
RAM	4GB	6GB	4GB	4GB	6GB
Expandable storage	Up to 400GB	Up to 400GB	Up to 2TB	Up to 2TB	Up to 2TB
Battery	3,000mAh	3,500mAh	3,000mAh	3,500mAh	3,300mAh
Fingerprint sensor	Back	Back	Back	Back	Back
Connector	USB-C	USB-C	USB-C	USB-C	USB-C
Headphone jack	Yes	Yes	Yes	Yes	Yes
Special features	Dual-aperture camera, water-resistant (IP68); super slo-mo video; wireless charging; iris scanning	Dual-aperture camera, water-resistant (IP68); super slo-mo video; wireless charging; iris scanning	Water-resistant (IP68); wireless charging; Gigabit LTE-ready	Water-resistant (IP68), wireless charging, Gigabit LTE-ready	S Pen stylus, water-resistant, wireless charging, Gigabit LTE-ready
Price off-contract (USD)	Varies: $720-$800 (64GB)	Varies: $870-$930 (64GB)	AT&T: $750; Verizon: $720; T-Mobile: $750; Sprint: $750; US Cellular: $675	AT&T: $850; Verizon: $840; T-Mobile: $850; Sprint: $850; US Cellular: $785	AT&T: $950; Verizon: $960; T-Mobile: $930; Sprint: $960; US Cellular: $963
Price (GBP)	£739	£869	£689	£779	£869
Price (AUD)	AU$1,199 (64GB), AU$1,349 (256GB)	AU$1,349 (64GB), AU$1,499 (256GB)	AU$1,199	AU$1,349	AU$1,499

Battery

Want a phone that'll last all day? The Galaxy S9 Plus has the bigger battery by far -- a 3,500mAh pack, compared to the 3,000mAh pack in the regular model. 

Yes, the bigger screen eats up some of that battery, but we still got 2 extra hours of battery life when we compared the Galaxy S8 Plus and the Galaxy S8 last year. They had the same battery difference, too. 

You might ask: Won't the S9 Plus's second camera make a difference? We doubt it, because the Note 8 also added that camera without sucking down extra juice.

Memory

The Galaxy S9 has 4GB of RAM, and the Galaxy S9 Plus has 6GB. 

That's probably not a big deal, though. As far as we're aware, Android phones mostly use RAM to keep lots of apps easily accessible when you multitask -- and unless you're a monster multitasker, 4GB is already quite a bit. That said, developers figure out ways to use more processing power and RAM each year.

For context, last year's Galaxy S8 and Galaxy S8 Plus both had 4GB, and the Note 8 had 6GB.

Price

Did you expect a phone called the "Galaxy S9 Plus" would cost the same as the regular model? Of course not -- you'll pay a premium. In the US, that means at least an extra $100, though it depends on where you buy it. 

Similarities

As you can see in our comparison chart above, practically everything else about these phones is the same on paper, and also pretty similar to the Galaxy S8 and S8 Plus from last year. 

Both of these phones still sport a 3.5mm headphone jack, removable microSD storage, IP68 water and dust resistance, wireless charging, Gigabit LTE connectivity (if you're lucky enough to have a local Gigabit LTE network), USB-C connectors and rear-mounted fingerprint sensors. 

And, new for 2018, both phones have the same new Qualcomm Snapdragon 845 (or Samsung Exynos 9810) processors, 128GB and 256GB storage options (outside the US), stereo speakers and slimmer bezels, plus a better position for that fingerprint sensor where you probably won't smudge your camera. 

So really, your choice is about whether you need a slightly bigger screen and battery, and/or a second telephoto camera. Not a bad showing for the smaller phone, eh?

Samsung Galaxy S9: Our hands-on first impressions.

MWC 2018 : All of CNET's coverage of the biggest phone show on Earth.