The EliteBook 755 has a better storage medium than most comparable spec laptops that have been around for around the same time as it. This laptop has an SSD storage media, whereas most similar spec notebook PCs that were launched around the same time as 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.
This portable PC's storage medium (SSD) is in fact the best storage medium across all portable PCs of a similar type and age to the EliteBook 755.
An HDD storage media is the worst storage medium amongst similar types of portable PC.