CD writer is a device using which one can write on the Compact Disc (CD). Now a days it is being used in commercial places to store the big amount of data on the CD.
A normal CD Rom can not be used to write on the CD but it used to read the data available on the CD.
Digital Video Disk (DVD) is a latest storage media on which a lot of data can be stored at a very high speed. IT is specially made for multimedia work. ADVD looks very similar to a CD but it holds about 7 times more data than a CD.