The Latitude 12 E7250 has a better storage medium than most medium processor cores notebook PCs that have been on the market for a similar time to it. This portable PC has an SSD storage media, whereas most comparable spec portable PCs that have been on the market for a similar time to it have an HDD storage media. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
An SSD storage media is actually the best storage medium amongst all portable PCs of a comparable spec and age to the Latitude 12 E7250.
The worst storage medium amongst similar types of portable PC is HDD.