The ThinkPad T450 has an SSD storage medium which is better than most notebook PCs of this spec and age. Most medium processor core laptops that have been available for around the same time as 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.
An SSD storage medium is in fact the best storage medium across all medium processor core laptops that have been around for around the same time as the ThinkPad T450.
Across similar types of laptop the worst storage medium is HDD.
If the storage medium of this medium processor core notebook PC is not good enough for you then you might also want to look at the DELL Latitude 12 E7250 (SSD).