The Lenovo ThinkPad X250 has an SSD storage medium which is better than the HDD storage medium found on most notebook PCs of a comparable type and age to it. 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 medium is actually the best storage medium across all notebook PCs of a similar age and spec to the ThinkPad X250.
An HDD storage medium is the worst storage medium across similar types of laptop.
We think you might also be interested in some of the alternative portable PCs that have an SSD storage media currently available including the Lenovo ThinkPad X240, or the DELL Latitude 12 5000 (£729.95) which is cheaper; or the Toshiba Tecra Z50, or the Lenovo L450 (£809.99) which has a better Rating.
Notebook PCs with a better storage medium that might also be worth considering include the Toshiba Satellite Z30 (£809.99) (SSD).