Are some CDs more robust than others?

I remember getting 3 Ion Storm games (2x Deus Ex, 1x Anachronox) and they ALL had problems with the mildest of scratches. But I just reinstalled Diablo 2 Lord of Destruction and this thing is a beast, it has all kinds of scratches and dirt on it and it works fine. So why do some discs just seem more resistant to scratches than others?