Hi,
The DRC is a global setting file about manufacturing of a PCB.
It makes it possible to choose a "cheap PCB manufacturer" or a "high performance manufacturer" without opening the board file.
The CHANGE section is to individually change the behaviour of a single item (via, trace, signal, polygon....) .
For example if you want "all" vias to be free of solder stop, then you should choose this in DRC. If you just want a couple if vias free of solder stop (maybe to use them as electrical test point), then you could add 'circles" in the solder stop layer.
It really makes sense that the setup is in the DRC. Some users find EAGLE difficult to use. It makes it more difficult and confusing if there are two or more ways to adjust the same parameter..
Klaus