The Lenovo Flex 2 has an HDD storage medium which is better than the SSD storage medium found on most notebook PCs of a similar age and type to it. HDD is a traditional storage drive which stores the information on magnetic disks. HDD drives are slower than other forms of storage such as solid state drives (SSD) and flash drives.
An HDD storage medium is in fact the worst storage medium amongst all laptops of a similar type and age to the Flex 2.
An SSD storage medium is the best storage medium amongst similar types of laptop.