The Mac Mini Late 2014 has an SSD storage medium which is faster than the HDD storage medium found on most desktop computers that were released around the same time as 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.
This desktop computer's storage speed (SSD) is in fact the best storage speed amongst all medium processor core personal computers that are a similar age to the Mac Mini Late 2014.
An HDD storage medium is the worst storage speed across comparable types of desktop computer.