to make an exact copy of an audio cd,
1. insert the disc and open itunes
2. click the cd in the left column, all tracks should have a check mark next to them,
3. in the upper right corner of itunes, click import, this rips the cd to your hd, format and bit rate can be set in itunes preferences,
4. the ripped songs will appear in the library in itunes,
5. create a new playlist and name it what you want.
6. drag and drop the songs from the library to that playlist
7. click burn in the top left corner of the itunes window. specify in itunes preferences>burning if you want to burn an mp3 or audio cd.when its done burning, you can delete the cd's tracks from the library and delete that playlist you made if you don't need them.
to copy a data cd, you can do it 2 ways:
1. insert the disc, double click it on the desktop, drag its contents to a folder on your hd.
then insert the blank cd, finder asks what youd like to do, click initialize, then name it, drag and drop the contents you have on the hd to the blank cd on the desktop, when its done copying, eject it, itll ask if you wanna burn it, click burn, it burns.
or
open disk utility from utilities folder, click the cd in the left column after it says gathering disk info, then click Image>New>image from "cd name", then save it to your hd, it copies that cds contents as a disk image on your mac where ever you save it, then eject that disk, mount the disk image and in disk utility, select it in the list on the left and click burn.