ISO vs Data Burn

[Alabaca]

Now I'm confused...
Till last day I always believe that to burn a XBOX game I need to do a XISO file, then burnit with Nero, and make a CDRW or DVD that will just open on the XBOX drive and cant be open on the PC Drive.
Last day I do my first DVD Data Burn, them I can see the files on my PC DVDROM, and it runs on XBOX to...
Can anybody explain me this ??? Don't the burned DVD or CDRW have to be only read on the XBOX drive ???