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
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.