Before busting out the tools, let’s put on our Ultra-vision goggles and get a glimpse inside. In fact, why not take a step further and compare the S21 Ultra (Left) and S20 Ultra (Right) under X-ray, after which the following differences are found:-

• The vibration motor and the SIM card tray have traded places at either end of the phone. This seemingly makes room for a slightly larger earpiece speaker.
• The periscope telephoto camera is also noticeably larger, likely for extra optical zoom levels.
• Lastly, the wireless charging coils got a minor makeover. The outer charging coils are thinner, elongated, and got a few extra windings. This may help with better efficiency over a bigger charging area.

Next, after case back is opened, the phone reveals its contains inside.

The same large adhesive gasket holds both the back cover and camera bump in place—but the bump can be carved off separately, making for some interesting DIY customization possibilities. And, unlike the S20 Ultra, the glass camera lenses can be individually replaced.

The guts seem a slight iteration over last year's S20 Ultra, with minor changes to the wireless charging coil and upper antenna assemblies.

The earpiece speaker comes out with the antenna assembly this go-round, which is an updated design we first saw in the Note 20—as opposed to being separately adhered to the frame in prior phones like the S20 Ultra.

After the motherboard is disassembled, there is the familiar friend from the S20 Ultra, the 12 MP ultra-wide, also making reappearance is the main 108 MP wide-angle camera, which has been slimmed down from a 26 to 24 mm equivalent focal length. One big change to the camera array: The DepthVision camera from the S20+ and Ultra has packed up and moved out, making room for a 10 MP ƒ/2.4 70 mm telephoto camera as the periscope's new roommate.

With the battery, It's very nearly the same battery from the S20 Ultra, with just a couple tiny updates.

If you need a refresher, you're looking at a 5000 mAh power pack, running at 3.88V for 19.40 Wh. (Last year's model ran the battery at 3.86 V, for 19.30 Wh.) This puts the iPhone 12 Pro Max's 14.13 wh battery to shame—along with, oddly, the Note 20 Ultra's seemingly-gargantuan 17.46wh power pack. 

The new in-screen fingerprint sensor on the S21 Ultra (right) is a whopping 77% larger than the S20's now-puny-looking one. On top of software improvements, the larger surface area lets you be more lax with finger placement, while also collecting more data per scan.

As seen from our X-ray shot earlier, the SIM card reader has moved from the top of the phone—where it was connected to the motherboard—to the bottom of the phone, now connected to the daughterboard, right next to the USB-C charging port.

Samsung is known for pushing the boundaries of what’s possible for a smartphone, but this seems more like a maintenance year for the Galaxy series—keeping the things that worked and getting rid of the nice-tries, resulting in a refined product.