Google Pixel Uses 15W Charging and Pixel XL Uses 18W Charging.
Google introduced the Pixel phones in two sizes - 5-inch and 5.5-inch. The Pixel and Pixel XL don't have many major differences; however the Pixel XL is bigger, a larger battery, and has a better display resolution, Now, thanks to tester Nathan K, a new difference has picked up between the two Google smartphones.
Nathan shows on his Google Plus page that in his tests, he establish that the Google Pixel does not reach the 18W charging wattage the tech giant had announced, and it maxes out at 15W. Once this data was released by the tester, Google established that there was an oversight in the product description and has established that the Google Pixel can charge with 15W while the Pixel XL can charge at the peak of 18W which was primarily claimed for both devices. "This decision was intentional and apparently made based on thermal concerns". The Pixel XL sports a 3450mAh battery, while the Pixel sports a 2770mAh battery.
Nathan says that this 15W limit is because of thermal concerns. This variance of 3W of power accounts for 20 percent speed boost in charging. Though the Pixel XL has a larger 3450mAh battery, so it will anyway time-consuming to charge. In real-world use, this difference won't be much and smartphones usually don't charge at peak speed at all times anyway.
As said, the Pixel XL smartphone sports a QHD display, while the Pixel smartphone sports a full-HD display. Google is giving out $50 in Play Store credit to Pixel buyers, who are however to get the phone due to shipping delays.
The Pixel and Pixel XL are Google's first phones with full control of the development process, even though the devices are being manufactured by HTC.