As expected, the Apple A12Z soc from the new iPad Pro is the same chip as the A12X from the previous iPad Pro models. With the A12Z variant, all eight GPU cores are enabled; while one GPU core is disabled with the A12X soc.
Research of TechInsights confirms that the A12Z is equal to the A12X. The company previously expressed this suspicion based on a first look at the chip. TechInsights has now extensively put the chip under the microscope and concluded that the assumption is correct.
Benchmarks also showed that the A12Z scores almost the same as the A12X, but that the GPU is slightly faster. This can be explained by the additionally enabled GPU core. With the A12X, one of the GPU cores was probably disabled to improve the yields. The production process has now been refined and the yields are probably better, so that the full GPU can be used.
Apple announced its new iPad Pro models in mid-March. The models with the A12X soc were released about 18 months earlier. At that time, the 7nm process on which the chip is made was still relatively young. The iPad socs have four powerful Apple Vortex cores and four frugal Tempest cores. With the A13-socs for smartphones, Apple uses its newer Lightning and Thunder cores.
Analysis of A12Z and A12X Socs by TechInsights