hard drive stores all your data.It houses the hard disk, were all your files and folders are physically located. A typical hard drive is a bit bigger than your hands also you can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid incasement. The data is stored on the hard drive magnetically, so it stays on the drive even after the power is turend of.
opticals are like lasers which can see and read data on optical disks. These disks include CD`S and DVDS, wich are made up of millions of small bumps and also dips. Optical drive have these lasers that read the bumps and dips as one`s and zeros which the computer can understand.