iPhone Duo and Xiaomi 18 Fold Diverge on Price, Cameras and Availability

The two devices are close in design and display. Both have a 7.6-inch inner screen when open and a 5.4-inch outer screen when closed, with 120Hz refresh rates. Xiaomi claims a peak brightness of 4,000 nits, while Apple lists 3,000 nits. The iPhone Duo's inner screen has a nano-textured layer that reduces glare and makes the crease less visible, and its front-facing camera is hidden beneath the display. Apple uses a titanium frame and Ceramic Shield glass and certifies the Duo IP68 for water and dust resistance. Xiaomi uses an aluminum frame with Shield Glass 3.0 and did not share an IP rating. The 18 Fold weighs 219 grams, compared with 254 grams for the Duo.

Inside, both phones use custom chips. Apple's A20 Pro is described as its most powerful mobile chip and the first built on a 2-nanometer architecture. Xiaomi's XRING O3 is based on 3-nanometer architecture. The 18 Fold has 16GB of RAM, while the Duo has 12GB. Xiaomi offers a 6,000mAh silicon-carbon battery and supports up to 67W wired and 50W wireless charging. Apple has not disclosed the Duo's battery specs, and the phone supports 60W wired and 35W wireless MagSafe charging.

Cameras are a major dividing line. The iPhone Duo has two 48-megapixel rear cameras, a main and an ultrawide, with no optical zoom. The Xiaomi 18 Fold has a 200-megapixel main sensor, a 50-megapixel ultrawide and a 50-megapixel sensor for optical zoom. Engadget notes that Apple is not offering its best camera setup on its most expensive iPhone. On software, the Duo runs iOS 27, which adds Split View multitasking and Siri AI, with Apple Pencil support arriving later this year. Xiaomi does not officially sell phones in the US, and local carriers do not certify them, so the 18 Fold remains a China-only option for now.

A separate Engadget comparison between the iPhone Duo and the iPhone 18 Pro focuses on what the Duo gives up in camera hardware. At $1,999, the Duo lacks the iPhone 18 Pro's telephoto lens and variable aperture. The Duo's two 48-megapixel rear cameras are a main camera and an ultrawide that also handles macro shots. Both the Duo and the 18 Pro can offer a 2x view by cropping into their 48-megapixel main sensors. The 18 Pro has a dedicated 4x telephoto camera that can crop its 48-megapixel sensor to make a 12-megapixel optical-quality 8x zoomed shot. The Duo's best is 2x optical-quality zoom.

That difference means the Duo is probably not a great choice for shooting distant subjects such as a performer on a concert stage or an athlete at a sporting event. Digital zoom can go beyond 2x, but quality suffers. Apple has not said why it left out a telephoto lens. Engadget suggests physical constraints may be the reason: a foldable opens into a bigger device, so its cameras must fit into one very thin half, and camera modules compete with other hardware, especially batteries, for limited internal space. Future Duo versions could still get a dedicated zoom lens, and other foldable manufacturers have managed to include one.

The Duo also lacks variable aperture, which is one of the iPhone 18 Pro's headline features. The 18 Pro can physically widen or narrow its aperture to adjust how much light enters and how much of the scene stays in focus. The Duo's aperture is fixed, as on previous iPhones. It still supports portrait-mode background blur, but that digital effect is not the same.

The Duo has camera features tied to its foldable design. It can stay upright and prop itself up when partially folded, acting like a built-in tripod for group photos and video calls. It has a 12-megapixel selfie camera on the outer screen and a separate 1080p FaceTime camera hidden beneath the inner folding display. The outer screen can act as a viewfinder for the 48-megapixel rear cameras, and when the Duo is opened all the way, users can point those cameras at their face while still seeing the shot. A feature called Smart Take recognizes when everyone in a group photo is ready and takes the photo automatically. Duo FaceTime lets someone nearby join a call using the outer display and camera, and Kid Cue shows Peanuts animations on the outer display to get children to look toward the phone.

The Duo and the iPhone 18 Pro still overlap in several areas. Both support 24-megapixel and 48-megapixel photos, adjustable portraits and updated Photographic Styles with texture and grain adjustments. Both can record 4K Dolby Vision at up to 120 frames per second and apply Cinematic effects after capture. The Pro's advantages appear when users want manual control. Thanks to its variable aperture, the 18 Pro offers Pro Controls for shutter speed, white balance and aperture. The Duo does not. The Duo also lacks ProRAW photos, ProRes, ProRes RAW and Apple Log 2.