The Apple Mac Pro Late 2013 has an SSD storage medium which is faster than the HDD storage medium found on most personal computers of a comparable type and age to it. Solid State Drives (SSD) store information in transistors on a circuit board rather than on optical or magnetic media. This has the advantage of being much faster than a traditional HDD drive.
An SSD storage medium is actually the best storage speed amongst all desktop computers that have been around for around the same time as the Mac Pro Late 2013.
An HDD storage medium is the worst storage speed amongst comparable types of personal computer.