The differences between the iPhone 12 and the iPhone 12 Pro models were thought to be only camera-based, but it turns out that Apple has also equipped them with different volumes of RAM. The increase in RAM for the Pro models should give them an advantage over the regular iPhone 12 and their predecessors, but an initial Geekbench listing offers up some rather disappointing multi-core performance.
https://www.notebookcheck.net/Apple-may-have-equipped-the-iPhone-12-Pro-and-iPhone-12-Pro-Max-with-6-GB-of-RAM-but-initial-Geekbench-result-is-a-mixed-bag-for-the-A14-Bionic.498047.0.html