Apple is using HBM2 ([1]) memory, pioneered by AMD for their GPUs. Essentially, yes - it's that, placing memory really close to compute and making a lot of channels for higher bandwidth.

1. https://en.wikipedia.org/wiki/High_Bandwidth_Memory

They use commodity LPDDR4X or LPDDR5 depending on SKU, for M1 and M2.

Thanks! I missed that.

uh no they’re not lmao. unless you’re talking about very particular intel machines no one cares about anymore.

HBM is RAM chip stacked on CPU chip, not an integral CPU+RAM on a single die.

No, in classic HBM multiple RAM dies are stacked on top of each other, but they sit next to the CPU, not on top. Edit: well typically it would be a GPU not a CPU.

Apple marketing made it sound like they were doing something special with RAM on their M socs. Really they mainly improved packaging form factor with run of the mill LPDDR5. It's questionable if this really does much for performance as the M socs still have worse memory latency than Intel and AMD chips.

Thank you. I indeed fell for Apple marketing.