Compared with the driver that was launched earlier this month, the only thing new seems to be support for the Oculus Asynchronous Spacewarp (ASW) feature. This is a software-based trick to squeeze more performance out of mainstream hardware by creating synthetic frames. According to Oculus, it's not the same as actually having higher-end hardware, but it should be good enough to get an enjoyable experience on a lower budget.
Support for Oculus’ Asynchronous Spacewarp (ASW) feature on select Radeon RX 400 series graphics products. ASW compares previously rendered frames, detects the motion between them, and extrapolates the position of scene components to create a new synthetic frame. Using this technology, synthetic frames will accurately approximate the fully-rendered frames they’re designed to replace.