take any music file on your computer. import it into a empty session in cubase (no fx/no busses /nothing) then bounce the track. do the same with garageband. there will be no difference
Most cubase session presets (Rockband recording/ Pop Song recording/ Dance Production etc) have fx busses already hooked up when you open them, which might enhance the sound of your recording?
the recording itself is 100% identical to what you would've recorded in garage band( if same sample/bitrate was used)