Hardware makers often source components from various vendors in order to meet supply demands. Those taking apart the new Apple iPhone 6s discovered there are two different A9 chips being used, one from TSMC and one from Samsung.
As reported by MacRumors, early battery tests and feedback from some users indicates that the TSMC variant may provide longer battery life than the Samsung model.
Testing by CNET is underway in order to validate these findings so until definitive results are provided don't run to the Apple Store to try to switch out your iPhone 6s.
The TSMC chip used a larger die size of 16 nanometers while the Samsung process used 14-nanometer. If you would like to check and see which chip you have, you can install the Lirum Device Info Lite application and read the processor type. If it reads N66AP (6s Plus) or N71AP (6s) then you have a Samsung chip. If it reads N66MAP (6s Plus) or N71MAP (6s), then you have a TSMC chip.
My new iPhone 6s Plus has a TSMC chip and I am seeing about the same battery life as I saw with my iPhone 6 Plus. Keep in mind that early benchmark testing shows there are no performance differences between the two chips. Battery life is the one area that requires further investigation.