A CD can store up to 700 MB of data through optical media and pits burned onto its surface. DVDs can store up to 4.7 GB of data and are commonly used to store movies and games. Hard disks can store the largest amount of data, are usually internal, and external hard disks are also available, while pen drives can store less data than hard disks but connect to systems via USB ports.

2.  A CD can store up to 700 MB data .
 The data is stored in it with optical media.
 Data is stored by making pits on its surface.
 CD-R (Compact Disc-read only)and CD-RW
(Compact Disc Re Writable) are two types of
CDs.

3.  DVD can store up to 4.7 GB data.
 DVDs are used for storing movies , games
,etc.

4.  Hard Disc can store a huge amount of data
than other storage.
 It is usually fixed inside the system cabinet.
 However , external hard discs are also
available nowdays.

5.  Pen Drive can also store a huge amount of
data but less than a hard disc.
 It is connected with the USB port available
on the system cabinet.

6. 
 Thanks