If you can not burn dick copy directly to another disk or you want to save the time in the case of many disks copy so using image burn is your better option because you don't have to read disk to disk from CD or DVD drive ,but image file will can store in your computer's hard drive and then burn directly to the disks.
If you are using Ahead nero 9.0 you have 3 options to burn image file
How to burn image file by using Nero Express
1 Put the original disk into the CD/DVD Drive
2 On NeroStartSmart click small Nero icon on the lower left side to open up the menu links ,then click on Nero Express
3 On Nero Express window click on "Image Project copy"
4 Click to select Copy entire Cd/Dvd
5 Specify the source drive as our CD/DVD Drive and the destination drive as Image Recorder
6 After you have finished ,then click on "Copy" command will open up new window
7 On the new window select the directory and enter the name of image file and click "Save"
8 Wait for the burning process to finish 100% and the drive will be ejected out ,click "OK" to finish