The main difference between SSD (Solid State Drive) and HDD (Hard Disk Drive) in laptops lies in their technology and performance. SSDs utilize flash memory to store data, enabling much faster read and write speeds compared to HDDs, which rely on spinning disks and mechanical components. This results in quicker boot times, application launches, and data transfers with SSDs. Additionally, SSDs are more durable and shock-resistant, as they lack moving parts.