The main difference between hard disk drives (HDDs) and solid state drives (SSDs) is the way they store and access data. HDDs use a spinning disk (platter) and a moving head to read and write data, while SSDs use flash memory chips that have no moving parts. This makes SSDs faster, quieter, and more durable than HDDs, but also more expensive and less spacious. HDDs and SSDs are both I/O devices that can be used to boot the system and store data, but they have different advantages and disadvantages depending on the use case. Reference:
Difference between Hard Disk Drive (HDD) and Solid State Drive (SSD)
Hard Disk Drive (HDD) vs. Solid State Drive (SSD): What's the Difference?
How to Check Whether Your Disk Is an SSD or HDD on Linux