All we really know for sure is that the Navi GPU inside each console will bring hardware-level support for real-time ray tracing. Beyond that, there is no official information outlining the number of compute units or stream processors, clockspeeds, or anything else on a technical level. But there have been some interesting leaks.
As the story goes, someone at AMD's ASIC validation team stored bits of internal testing data on GitHub. These data fragments are said to represent various designs that are a work in progress, including the PS5 chip, which is now codenamed "Oberon."
The leaked data is several months old, and things could have changed since then—specs, features, drivers, and so forth. That said, more recently leaked tests "confirm" the Navi GPU inside the PS5 will have 36 custom GCN CUs running at 2GHz, which translates into 9.2 teraflops (TFLOPs) of raw performance.
New information also suggests the PS5 will sport GDDR6 memory, which is not surprising, with a rated bandwidth of 448GB/s (or even higher if going with 16Gbps chips on a 256-bit memory bus, instead of 14Gbps chips).
According to Leadbetter, the aforementioned leak mentions a processor named "Arden," which is likely the GPU inside the Xbox Series X. It points to Arden having 3,584 shaders, which works out to 56 CUs. If 12 TFLOPs is accurate, then a clockspeed of 1,680MHz would be needed to achieve that, given the rest of the specs (1,700MHz would bump that up to 12.2 TFLOPs).
There's much more to read on topic, which you can do by hitting the link in the Via field below. Just bear in mind that none of this is official. Furthermore, specs and designs could change, with launches of both consoles being a year away.