There's a little drama brewing less than two weeks after Apple released it's brand new line of iPhones. As reported by Anandtech, the A9 processor of the iPhone 6s and 6s Plus were dual sourced from Samsung and a company called TSMC. The differences between these chips was not evident for some time as fans assumed the smaller 96mm² by Samsung would be the superior chip. Users are conducting tests and reporting the results via forums on Reddit and Mac Rumors which have resulted in the conclusion that the TSMC A9 has approximately 2 hours better battery performance than the Samsung.
[reddit user test done multiple times]
A developer called Hiraku Jira has released an unsigned program (install this at your own risk) to identify which chip is in a specific device and is charting the results of everyone who tests their device. 70% of 6s phones have the TSMC processor while only 40% of 6s Plus phones have the TSMC inside.
Another (potentially safer) method of identifying your processor is though a free app called Lirum Device Info Lite directly from Apples own App Store. Just open the app and look at the main page under "Model" the results are:
N66AP (6s plus) or N71AP (6s) - Samsung chip
N66MAP (6s plus) or N71MAP (6s) - TSMC chip