At this point, Apple knows that it has to prepare a lot of iPhones for a new launch, which was certainly the case this time around. As a form of redundancy, making as many processors as possible is one way to make sure there’s enough stock to go around (at least for those that pre-order).
Now, according to Chipworks, there’s a bit of size variation in the A9 processors out there in the wild, which are currently found in the iPhone 6s and 6s Plus. According to the publication’s research, there are actually two sizes, and the one manufactured by Samsung (part number APL0898) is 10 percent smaller than the chip manufactured by TSMC (part number APL1022). That could actually bear some performance differences.
If Samsung’s processor is indeed ten percent smaller, then it means it could be produced on a smaller die size, which could mean that it’s more power efficient than TSMC’s larger processor.
As it stands, Chipwork is currently still in testing, so any performance differences will be found along the way. If they are discovered, we’ll be sure to update here accordingly.