At this point, I don't think that's entirely clear. Something to do with the way Apple has tightly integrated the SoC parts and the OS's memory management lets them get massively more performance out of much lower-specced machines, and at least from what I've seen, no one has yet managed to truly unravel all that makes this possible.
I'm interested in this because I have a maxed 2018 intel mac mini and loaded it to 64gb of RAM. I want to ditch my eGPU and go to Apple Silicon on the next release.
I wonder if the memory performance should be so surprising. Because haven't people been bemoaning the "low" amount of ram in iPhone / iPad?
iPhone had 4GB on XS, and 11. And only went to 6GB on the Pro models. Yet the performance and benchmarking on these devices has seemed to garner praise with each successive generation.
Sort of like when people compare nm of processes on the chips. You can't just say "oh, their number is smaller, it must be better."
To be sure a device with 16GB of M1 RAM should be more competent than 8GB of M1 RAM, but now that's apples to apples.