What happens when you download a game to your xbox 360 hard drive?

i saw an option to download a game to my 360's hard drive.





i was wondering, does the game still work after downloading it, like the actual disc.





and could i play the disc on a different system?





and do you need the game to play the hard drive download?|||You need to have the game in the xbox to play the game so nobody downloads the game to the hard drive then sells the game, downloading it to the hard drive makes the game boot up faster and yes the regular disk will work on other xbox 360 systems|||It's kind of stupid!





You actually completely play the game from the hard drive, but you still need the disc in the machine to play it to prove you own it!





It's quieter because the DVD isn't actually spinning so I guess it saves on wear and tear on the disc too. It also improves load speeds!|||You still need your disc to play.