The Chromebox has an SSD storage medium which is faster than most similar spec PCs that have been available for a comparable time to it. Most similar spec PCs that have been around for a comparable time to it have an HDD storage medium. 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 PCs of this type and age.
An HDD storage medium is the worst storage speed amongst comparable types of desktop computer.