Music CDs

I have a CD "The Best of the Big Bands'. it has 31 songs on it,, a littleover an hour. Tried buurng it on to one of my blank CDs using ITunes. It said I would have to put it on two CDs, not enough room on one. I did this and it worked but how come the original could put over an hour on it.? My daughter went to get some DVDs but was told you couldn't put music on them. Something isn't computing. It does look like the original was also a copy with a covering put on the disk which shows CD but maybe its not. It is not digatal becasue I can play it on my portable CD player.