I don't think just because Blu Ray has a higher compression rate and can fit a lot more information on it makes it a different format. Isn't it just an improved DVD? Isn't this whole Blu ray thing a marketing scheme? And the fact that it requires a different kind of player doesn't mean it is a different format. When Hybrid cars that ran on battery power came out we didn't stop calling them cars, did we?
So how can Blu Ray be a different format than DVD?
So how can Blu Ray be a different format than DVD?