The Sony Xperia series' newest models are the Xperia XZ1 in middle size and the Xperia XZ1 in compact size. Let me go through their shared characteristics and different characteristics.
Snapdragon 835, the highest class SoC, is adopted for both models.
The Xperia XZ1 is a successor to the Xperia XZs, and it is the core model of this series. It has a 5.2-inch LCD that supports 1080 X 1920 FHD. It is 73 X 148 X 7.4 (WHD mm), and it weighs about 156 g. It is wider than Xperia XZs by 1 mm, but it is 0.7 mm thinner, and it is lighter by 5 g. There is not much difference in its look, but thanks to the half sphere design of the sides and thin body without seams, it fits nicely in your hands.
The Xperia XZ1 Compact, on the other hand, is a successor to the Xperia X Compact. It has a 4.6-inch LCD that supports 720 x 1280 HD. It is 65 X 129 X 9.3 (WHD mm), and it weighs about 143 g. Compared to the Xperia X Compact, it is thinner by 0.2 mm, and it is heavier by 8 g. Also, this uses a glass fiber reinforced plastic (GFRP) and has integral structure, which makes it stronger and provides better radio permeability.
Both the Xperia XZ1 and the Xperia XZ1 Compact have high-end CPU Snapdragon 835 MSM 8998 (2.45 GHx x 4 + 1.9 GHz x 4), which has been adapted with the Xperia XZ Premium, and a big 4GB RAM. The Xperia XZ1 scored 176,224 for overall score (3D:71187,UX:58397,CPU:38329,RAM:8311)with AnTuTu benchmark test, and the Xperia XZ1 Compact had an overall score of 161,877(3D:58549,UX:56625,CPU:38644,RAM:8059), which means they are one of the smartphones with best performance among current smartphones. Also, when I compare the sub scores of these two devices, the scores of CPU and RAM are almost the same, but they have differences in 3D and UX which both show performance in graphics. I am investigating the reasons why. Having said that, I couldn't feel the difference coming from the score in images or switching between apps.
Its battery capacity is both 2,700 mAh. The battery life calculated from average users' usage is about 100 hours for the Xperia XZ1 and about 140 hours for the Xperia XZ Compact. The previous model Xperia X Compact's battery life was about 95 hours. It's worth being mentioning that both processing performance and battery life have been improved.
The main camera is about the same as the Xperia XZs, and the front camera of the Compact supports ultra-wide angle.
Like the Xperia XZs, both have 19 MP image sensor, RGBC-IR sensor which senses actual white balance, and laser AF sensor that realizes fast automatic focusing even in dark environment. As for its functions, they also have succeeded super slow motion video and triple image sensing technology from the Xperia XZs. They also have new functions like predictive capture (smile) and autofocus burst. UI for manual shooting has been improved, too, and operation now is easier to understand.
As for the front camera, on the other hand, they are different. The Xperia XZ1 has a 13 MP image sensor whereas the Xperia XZ1 Compact specializes in taking selfies with an 8 MP image sensor with ultra-wide-angle lens. It also has a new feature called display-flash in which the display flashes and not the flash when taking photos. It means it is less likely to take not-so-good selfies even in dark environment.
It has Android 8.0, but its function, Picture-in-Picture, is not supported fully.
Although the Xperia XZ1 and the Xperia XZ1 Compact have Android 8.0 as OS, the use of Picture-in-Picture feature, which you can play movies in a small window, is limited just like the Nexus series, the reference model. Google's original YouTube App is not compatible with this function, and Xperia's original app for playing movies or TV programs also do not support PinP. It can be used only with Chrome web browser and the GPS of Google Map.
Both have 3D Creator, the original 3D capture app, preinstalled. You can scan colors and shapes of objects like people's or dolls' faces and food using a built-in camera and make 3D data. The 3D data taken can be used to make a figure using online 3D print service or to make a 3D avatar to play as AR effect data or 3D animation.
Including the Xperia XZ Premium, now there are three devices in different size.
The Xperia series this winter include the Xperia XZ1 and Xperia XZ1 Compact, which we have seen here, along with the Xperia XZ Premium, which had been released before them. These 3 models are different in terms of its body size, display size and resolution, but they have the same CPU and RAM capacity. Also, the Xperia XZ Premium is planned to be updated to Android 8.0 in December, so they share the same software, too. All these are the very smartphones users would want Xperia to be, high in performance and multi functional, so you cannot go wrong as long as you choose the size you like.