In my opinion you need both. Games that don't need patching are best copied with CloneCD. For best results ensure that your burner can handle DAO+96 RAW mode; the Elaborate Bytes site lists compatible burners and what they handle.

CDRWin is necessary when you have to patch a game. Usually that is to defeat copy protection or to patch the game to work with a particular pboot method.

Your burner needs, of course to be compatible with both programs.