Based on the three smartphones that have been released for comparison. Each is more famous than its predecessor, and they both share several similarities and differences.
Sizes and Displays
The Moto X 2014 and Xperia Z3 have the same 5.2 inch display, 424ppi pixel density and 1080 x 1920 resolution.. The Moto X however has a Corning Gorilla Glass 3 protected AMOLED display, while the Xperia Z3 is outfitted with IPS LCD protection on the back as well. The Z3 is water and dust resistant, and the Moto X has a coating that is waterproof. The One M8 has a smaller Super LCD3 5 inch display, with an increased 441 ppi pixel density and same resolution. Like the Moto, it is protected by Corning Gorilla Glass 3. The thinnest at 7.3 mm is the Xperia Z3, and the thickest at 10mm is the Moto X 2014. The heaviest however at 160 grams is the HTC One M8.
OS and Hardware
They each are powered by the same quad-core Krait 400 processor at 2.5GHz. However, the Xperia Z3 and the Moto X 2014 runs on a Qualcomm Snapdragon 801 MSM8974AC; that is better than One M8’s MSM8974AB. The HTC One M8 has two variants, in which the other is powered by an US/EMEA processor at 2.3GHz. Each device uses Adreno 330 GPU, and they each have the same internal storage options of 16 and 32GB. The One M8 and the Xperia Z3 allow for 128GB of expandable memory. The Xperia Z3 has a RAM capacity of 3Gb, while the Moto X 2014 and the One M8 have a RAM capacity of 2GB. The Xperia Ze and the Moto X 2014 run on the Android KitKat v4.4.4 and awating the Lollipop 5.0 upgrade. The One M8 for now runs on the KitKat v 4.4.2.
Camera
The best camera belongs to the 20.7MP back shooter on the Xperia Z3. It has features that includes the 1/2.3 inch sensor size, autofocus, LED flash, and more. The 13MP on the Moto X is sufficient with a dual-LED flash, compared to the 4MP Ultrapixel One M8 back camera. The front 5MP camera is better than the 2.2MP shooter from Xperia Z3 or the 2MP shooter from Moto X.
Battery
The Moto X with only removable device is also the smallest at 2300mAh. The One M8 has a bigger 2600mAh unit, while the biggest at 3100mAh belongs to Xperia Z3.
Price
The Moto X 2014 can be found for $500, on Amazon, as well as the HTC One M8 for $558, and Xperia Z3 at $630.