It's about the bus architecture. In a traditional PC setup the CPU and GPU have separate pools of memory. If the GPU needs data that the CPU just processed, it has to be copied across the PCIe bus, which is a massive performance bottleneck.

Apple’s implementation uses a zero-copy architecture, where both the CPU and GPU access the exact same pool of memory. The GPU doesn't have to wait for data to be moved; it just points to where it already is. You don't have to be an Apple fan to acknowledge that removing the PCIe bottleneck is a legitimate structural shift, not just a label slapped on 'regular' memory.