There are two different configurations of the Vaio Pro 13 in the wild. All have on a similar form factor SSD but on some of the "pre-configured" models this is

There are two different configurations of the Vaio Pro 13 in the wild. All have on a similar form factor SSD but on some of the "pre-configured" models this is connected via a SATA3 bridge rather PCIe. On the models with the PCIe the performance is equivalent (or close enough, within a few percentage) to that of the new machines from Apple.