If he is talking about silicon, could be XSX used less EUV around transistors, would explain the lower frequency. No its not just because super cool when parts are 2.5 GHz.
If its all just talking about GPU logic and functions, then could be a whole raft of things, there has been numerous AMD and Sony patents on data compression between caches, pixel vertices and so on, some of them Sony.
Then there is all the L1 ache being common for some functions (I dont think this is gaming tbh), infinitiy cache which is large L2 I believe to negate bus width but also will help with cache misses to memory. Could be huge, but also could be massive perf gain.
The unusual thing here is the PC parts are coming after consoles, so will they look more like ps5 or XSX architecture ? As they are very very different, and anyone yhings they have employed the same is just wrong..
What is RDNA2 is the question, is it process + logic blocks, clock speed of GPU and fast caches...Is it TF

or efficiency of moving data around really fast.....All this talk of vRS and mesh shaders is likely so far off the mark in what will give the performance boosts is my opinion, but we aint got long, 28 th Oct, 2 weeks !
RDNA2 is a marketing term really, we just have to look at what features are present, similarities to PC parts as they seem to be coming last so AMD can pick and chose what is best, and at the end of the day how they perform is what matters..