Apple has really cranked up the speed on their current line of MacBook Pro in recent years, thanks to PCIe solid state hard drives. Most computer companies install traditional mechanical drives, while some other companies install SATA solid state drives, but Apple has taken storage to another level. SATA SSDs top out around 550MB/s, while PCIe solid states allow for a whopping 1,250MB/s!
There is also a significant physical size difference between both. The new PCIe SSDs are a lot smaller than their SATA-based counterparts which means faster, thiner laptops. Now drive manufacturers are discussing storage capacities on these drives going up to 10 Terabytes thanks to 3D NAND technology currently in the works from Intel.