SSDs have a higher processing speed, shorter read and write times, and low latency. This is because they use electrical circuitry and have no moving parts, unlike HDDs. SSDs are smaller and more power-efficient because they have no external mechanics or motors attached to the drive. SSDs have a higher bandwidth than HDDs. A typical HDD will deliver a read/write speed of 80-160MB/s. On the other hand, a typical SSD will deliver read/write speed of between 200 MB/s to 550 MB/s.
SSDs are quite reliable, since they have no moving parts and because of this can withstand some level of extreme and harsh environments and may even withstand accidental drops, shocks, or vibration but they have a finite number of reads and write before they fail. SSDs have a higher cost per GB (For example, a 1 TB SSD Samsung 870 EVO costs ~$100 but a 1TB HDD Seagate BarraCuda costs ~$45. In this case, the SSD costs $0.1 per GB and the HDD costs $0.045 per GB) and could not store as much data as HDDs (Comercial SSDs have a storage capacity of 120 GB to 4 TB max, HDDs could go from 250 GB to 14 TB).
HDDs have a lower cost per GB and higher storage than SSDs. However, HDDs are VERY fragile, they could fail if they are handled roughly or dropped they could fail. They are less reliable due to the possibility of mechanical failure, like head crash and susceptibility to strong magnets. They generate heat, use more power, are heavier, higher latency, lower speed, and lower bandwidth. Finally, HDDs usually suffer from disk fragmentation, which means files are divided into pieces and scattered around the hard drive. This will slowdown speed and because the File System have to search through different parts of the hard drive to put together a single file. The cause of disk fragmentation is the frequent creating, deleting, and modifying of files. To fix you need to defragment your HDDs regularly.
I hope this helps <3