Specifically, the M1 Max has twice the memory controllers, and each one comes with a cache block, and hence has twice the cache. It also has twice the GPU cores

Specifically, the M1 Max has twice the memory controllers, and each one comes with a cache block, and hence has twice the cache. It also has twice the GPU cores, an extra ProRes core, two extra display controller cores, an extra AVE (video encoder) block, an extra scaler block, an extra PMGR (power manager, including some PLLs and such) block and extra bus fabric branches to drive it all, and two things Apple won't talk about: an extra ANE (Neural Engine) (disabled on all shipping machines) and die-to-die interconnect. This is all in the lower chunk of the die, such that they could basically cut the design on the dotted line for the M1 Pro (not literally, but almost; they definitely didn't redo much if any P&R, as the shared portion is identical by all visual and logical appearances).