The GeForce GTX 1070 Founders Edition is based on the same GPU as Nvidia's GeForce GTX 1080, only with 25% of its CUDA cores and texture units disabled. Though, the processor's back-end still serves up 64 ROPs and 2MB of L2 cache. Also, GDDR5X memory is replaced with standard GDDR5, while the 1070 sports a less sophisticated cooling solution and a lower power target of 150W.
The Founders Edition board is actually what Nvidia used to call its reference design. This time around, however, the company decided it wanted a piece of the premium card sales as well. Renaming its own offering is supposed to help sidestep the negative connotation that sometimes accompanies reference implementations.