The difference between memory and storage is that memory is open you can take information out form it you can use it,but storage you cant use it its saved information. It's just like kept there. Stuff you can see is optical storage. The way a CD works is that there are three parts of the CD rom. The labiling the inside of the CD and the reflected metal surface the other side is plastic. The most delicated part of the disk is on the front. A CD has millions of pites. The laser shines on the disk eaither it goes or the light doesn't go . There are 8 bites on a bite. There are 5 0000 00000 billion bites on a disk. When you scartch a disk it won't work it will damage it. The worest scartches a CD can have is on the sideway and round. If you have an old CD you can put a little bit of tooth paste on the scatch,but dont use it on a new CD. When you want to clean a CD use it from the center to the sides. Hard drive is not optical media, its magnetic media floppy. Inside the floppy disk is storage, there are millions of magnets in it. There are two pols. Magnets are eiather North or South. You can use magnets for bindary code. The magnets can screw up the floppy. There are billions of little magnets that goes North and South. They all store information in bindary.