When the 2020 iPad Pro was first announced by Apple last week, it was reported that the A12Z Bionic was only a marginal upgrade over the A12X Bionic chip found in the 2018 iPad Pro. The A12Z Bionic had an 8-core GPU while the A12X Bionic packed a 7-core GPU. A new report now claims that the A12X and A12Z Bionic are actually the same chips.
The A12X Bionic chip inside the 2018 iPad Pro actually shipped with an 8-core GPU but Apple disabled one of the cores. It is actually quite common for companies to ship their CPU and GPUs with one or a few cores disabled due to binning reasons or to launch a higher-end SKU later on with more horsepower.
In this case, it is likely that Apple disabled one of the eight GPU cores on the A12X Bionic chip on the 2018 iPad Pro due to binning reasons. As the yields have improved, the company realized that it could ship the A12X Bionic with all the eight GPU cores enabled. So, it presumably decided to rebadge the A12X Bionic as the A12Z Bionic and use it inside the 2020 iPad Pro.
The eight-core GPU of the A12Z Bionic is not noticeably powerful than the A12X Bionic. It brings about a performance improvement of around 5-7% in benchmarks which is not really much. It is very rare to see Apple ship its devices with such a small performance boost compared to their predecessor. Apart from the slightly faster GPU, the only other notable upgrade on the 2020 iPad Pro is the inclusion of a LiDAR scanner.You can read about all the differences between the 2018 and the 2020 iPad Pro here.