The key differences between SSDs (Solid State Drives) and HDDs (Hard Disk Drives) involve speed, durability, and architecture. SSDs use flash memory, which allows for faster data access and retrieval compared to HDDs, which rely on spinning disks. This results in significantly quicker boot times and file transfers with SSDs. Additionally, SSDs are more durable because they have no moving parts, making them less susceptible to physical shocks than HDDs, which can fail due to mechanical issues.