Any difference in burned game and store bought game?

I don't have a dreamcast, but I'm just wondering a few things.

According to this site, it is impossible to copy the whole DC game because of the special section on the disc which has its pits closer together like a DVD, but somehow "Utopia" or something is able to copy the readable part and make (all parts of?) the game an ISO which people download and burn and it works in their dreamcast, correct? If they don't have the DC game info from the special section on the disc, what is the difference in a Utopia ISO game and a store bought DC game.

In short, what is the difference in playing a store bought game or the ISO you downloaded off the internet and burned?

Are the graphics better on the store bought one or is there more to the store bought game or are they the same or what?

[gtk_8]

Well, im not sure how many games are like this. But, for instance in Tony Hawk 2, Echelon downsampled the fmv's to make it fit on a cdr. So, they're a little less quality. I believe most games are normal though.