This post explains how the hard disk operates during the process of storing or data retrieval. It is also a secondary storage media.
A hard disk contains one or more platters that are stacked on top of each other though not touching each other.
They are stack on a spindle which when rotates the platters form a cylindrical image.
As the disk rotates the read-write head moves in and out over the surface to record or read data.
Hard disks provide efficient data transfer and large storage capacity.
Also read: installing a hard disk
SSDs unlike the traditional HDD, they are made up of intergrated circutes which are used as memories. They do not have any moving mechanical parts.
this makes SSD typically more resistant to physical shock, run silently, have lower access time , and lower latency.
on the other hand, hybrid drive or solid state hybrid drive (SSHD) is a combination of features found in both HDD & SSD resulting to some bigger device.
Mark you; though over time the SSD costs have been reducing, a cheaper one could cost averagingly four times compared to a HDD of a similar unit.