After reading the dottrace documentation I realized that:

1. Dead objects are objects deleted before the end point of the snapshot.
2. Garbage objects are objects allocated after the starting point and deleted before the end point - in other words, "Garbage objects" is a subset of "Dead objects".

But after doing some profiling sessions, I could see that sometimes the number of "Garbage objects" is by far greater than the number of "Dead objects" of the same class (for example System.String). How should I interpret this phenomenon?