Because of their lack of internal moving parts, SSDs will last longer than HDDs which consist of a spinning disk and a platter which must move to read the magnetic data on the disk.
HDDs are also prone to physical damage from impact or shock. If you drop a HDD there is a likely chance that the moving parts inside will make contact with one another which can cause damage resulting in data loss. In the event of a dead SSD, the data can be recovered.
SSDs can start to slow down over time from repeatedly reading and erasing data from them but will typically outlive the system they are in than they are to be thrown out because of performance issues.
