The EliteBook 725 G2 has an SSD storage medium which is better than most portable PCs that have been around for around the same time as it. Most laptops of a comparable type and age to it have an HDD storage medium. 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.
This laptop's storage medium (SSD) is in fact the best storage medium amongst all comparable spec laptops that were released around the same time as the EliteBook 725 G2.
Amongst similar types of laptop the worst storage medium is HDD.