The primary difference between Solid State Drives (SSDs) and Hard Disk Drives (HDDs) lies in their data storage technology. SSDs use flash memory for storing data, offering faster access speeds, lower latency, and better durability because they have no moving parts. In contrast, HDDs use spinning magnetic disks to read/write data, which makes them slower and more prone to mechanical failure. However, HDDs typically provide larger storage capacities for lower costs, making them suitable for large-scale data storage needs. Users often choose SSDs for performance-sensitive applications.