Q. Diffrence between CD-R vs CD RW?

A CD-R disc looks same as a CD. Though all pressed CDs are silver, CD-R discs are gold or silver on their label side and a deep cyan or green on recordable side. Silver/cyan CD-Rs were created since green dye used in original CD-R doesn't reflect shorter-wavelength red lasers used in new DVD drives. Cyan dye employed in CD-R will enable complete compatibility with DVD drives. CD-R disc has four layers in place of three for a CD. At the lowest level laser light suffices to detect absence or presence of pits or marks on recording surface to read the disc. At the higher level it can in fact burn marks in the surface. 

CD-RW is relatively new technology however it has been gaining market share quite rapidly. The drives cost little more than CD-R drives since they can be used to play audio CDs and CD-ROMs as well as playing and recording CD-RW discs. A CD-RW disc comprises two more layers than a CD-R. The difference is the recordable layer is made of a special material, an alloy of several metals.  

Iomega Corporation has announced a CD-RW drive, the Iomega 48*24*48 USB 2.0 external CD-RW drive. These drive features buffers under run protection that list user's record safely even whilst multitasking. It provides plug-&-play capability with Microsoft Windows and Mac OS operating systems and its digital audio extraction rate (DAE) of 48x permits users to rep or burn a 60-min CD in fewer than 3 min while maximum drive speed is obtainable only with hi-speed USB 2.0 connections.